Turner and Verdugo were convicted under an indictment charging that on or about July 28, 1964, in San Francisco, California, they fraudulently and knowingly sold and concealed and facilitated the sale, concealment and transportation of 2.695 grams of heroin which had been imported into the United States unlawfully, as appellants knew.

The government’s evidence as to the transaction was as follows. Prior to July 28, Agent Chesley of the Federal Narcotics Bureau received information from an informer named Wilson that appellant Verdugo was dealing in narcotics. On that date Agent Chesley and Wilson went to the vicinity of 24th and Folsom streets in San Francisco, between six and seven in the evening, to meet Verdugo and to purchase narcotics from him if any were available. Wilson told Agent Chesley that they were to meet Verdugo in the Latin Circle bar on 24th Street.

When Wilson and Agent Chesley entered the bar, appellant Turner was playing a pinball machine. Wilson asked Turner if Verdugo was there. Turner said, “No. He was here, but he’s gone. He will be back.”

*602 Wilson and Agent Chesley then went to Glady’s Cafe, which was nearby. Verdugo entered the cafe a few minutes later, walked over to Wilson and said, “I told you the other place.” Wilson responded, “We were there. Where were you?” Wilson then asked Verdugo, “Can we still get the two spoons ?” Verdugo replied, “Yes, at the other place in a couple of minutes,” and left. Wilson and Agent Chesley waited a few minutes, then left the cafe and returned to the Latin Circle.

Turner was still at the pinball machine. Wilson asked him if Verdugo was “around.” Turner replied, “No, but he will be here.” Wilson and Agent Chesley sat down fifteen to twenty feet from Turner. In a few minutes Verdugo entered the bar and joined them. Wilson asked Verdugo if they could “get the two spoons.” Verdugo said that Agent Chesley looked like “heat,” but was assured that Agent Chesley was not a police officer. The terms of the purchase were agreed to. Agent Chesley handed Wilson $140 in official advance funds. Wilson passed the money to Verdugo. Verdugo then said to Wilson, “Go see that guy over there,” indicating Turner at the pinball machine.

Wilson walked over to Turner. Turner bent down toward the floor. He then handed a tinfoil-wrapped package to Wilson.

Wilson carried the package back to Verdugo and Agent Chesley and handed it to the latter. Verdugo said to Wilson, “Hey, your cut’s in there. I give you a little good taste”; and then to Agent Chesley, “Take it easy on that. That’s good stuff.”

Subsequent examination and analysis of the contents of the package disclosed approximately two “spoons” of heroin.

Both appellants took the stand. Turner testified that he was not in the Latin Circle bar on July 28, 1964. He testified, however, that he was frequently there around the middle of August; that he saw Wilson, alone at the bar once in August at about two o’clock in the afternoon; that Wilson asked Turner for some matches; that he, Turner, reached down and picked up some matches from a window ledge and threw them on the pinball machine; and that Wilson picked them up. Turner further testified that he had never seen Wilson and Agent Chesley together; that he had no dealings with Wilson in July 1964; that he had not seen Agent Chesley in July 1964; and that he did not recall any incident like that testified to by Agent Chesley.

Verdugo testified that Agent Chesley had arrested him on another charge in January 1964 and that in July of that year Wilson, accompanied by Agent Chesley, approached him in Glady’s Cafe. Wilson asked if he had “anything,” but he recognized Agent Chesley as “heat” and told Wilson that he did not know what he wanted, and to let him alone. Verdugo further testified that he was in Glady’s Cafe and the Latin Circle bar practically every day during July and August, but not on July 28. On that day he was “round my house some place, playing around.” He denied that the events testified to by Agent Chesley had occurred.

A brief review of the statute 1 in the light of recent decisions 2 will be useful in considering appellants’ contentions.

*603 The first paragraph of section 174 creates an offense having the following elements: (1) participation in a transaction involving narcotic drugs in any one of the ways specified in the statute (importation, receipt, concealment, purchase, etc.); (2) commission .of this physical act “fraudulently or knowingly”; (3) illegal importation of the narcotic drug; and (4) knowledge of the illegal importation.

The second paragraph of section 174 permits the trier of fact to infer guilt from unexplained possession of the narcotic drug by the defendant. This inference is constitutionally permissible because in common experience possession of such a substance, otherwise unexplained, is probative of the existence of all the elements of the offense, that is, there is a rational connection between the fact proved and the facts inferred. Yee Hem v. United States, 268 U.S. 178 , 45 S.Ct. 470 , 69 L.Ed. 904 (1925).

It remains the right of the trial judge to direct a verdict or enter a judgment n. o. v. when the evidence as a whole is insufficient to support a conviction as a matter of law, notwithstanding proof of possession. And although the evidence as a whole meets this minimum standard, it remains the function of the jury to determine whether that evidence, including the evidence of possession, establishes each element of the offense beyond a reasonable doubt. United States v. Gainey, 380 U.S. 63, 68-70 , 85 S.Ct. 754 , 13 L.Ed.2d 658 (1965). 3

We turn to appellants’ contentions, considering first those of appellant Turner.

Turner argues that even if the government’s version of the facts is accepted, he had physical possession of the narcotics for only a moment and such fleet *604 ing contact is not sufficient to bring the section 174 inference into play. He contends that without the aid of the statutory inference the evidence was insufficient.

As we have suggested, the sufficiency of the case against Turner is not to be tested by considering the evidence relating to the duration of possession (or to any other relevant fact) in isolation, followed by an examination of the remaining evidence. The question is whether on the whole evidence, including the inferences reasonably drawn from it, the jury could reasonably conclude that all of the elements of the offense had been established beyond a reasonable doubt.

We think the jury could properly infer from the government’s evidence, as we have briefly summarized it, that Verdugo arranged to sell Wilson two “spoons” of heroin at the Latin Circle bar on July 28, that Turner was party to these arrangements after the fact if not before, that Turner agreed to participate by holding the heroin in his possession at the planned place of delivery until the money had passed, so that it might not be found on Verdugo’s person in the event of trouble, and that Turner played the part he had agreed to play. The inherent improbability of Turner’s own testimony added substantial strength to these inferences. 4 Thus the evidence viewed as a whole, including Turner’s possession of the drug and all the circumstances surrounding that possession, was sufficient to establish that Turner facilitated the sale and concealment of the two “spoons” of heroin, and that he did so “knowingly” — with actual knowledge of the nature of the transaction, the substance involved, and the significance of his acts, or with “a conscious purpose to avoid enlightenment.” Griego v. United States, 298 F.2d 845, 849 (10th Cir. 1962).

The remaining essential elements are unlawful importation and Turner’s knowledge of it. Common knowledge that importation or domestic production of heroin is prohibited by law afforded a sufficient basis for the jury’s determination that this heroin was in fact unlawfully imported, absent evidence that the drug was part of the miniscule supply lawfully imported or domestically manufactured. Cf. Erwing v. United States, 323 F.2d 674 (9th Cir. 1963). And the jury could also conclude that what was common knowledge to it was known to Turner, a person shown by sufficient evidence to have knowingly engaged in the clandestine sale of the subtance, absent evidence of lack of knowledge. Cf. United States v. Llanes, 374 F.2d 712, 715-16 (2d Cir. 1967); Chavez v. United States, 343 F.2d 85, 90 (9th Cir. 1965); Griego v. United States, 298 F.2d at 848 .

No constitutional problem was presented by the court’s instructions permitting the jury to infer illegal importation and knowledge from Turner’s possession. The jury could obviously have found that Turner was in possession and control of the heroin during the entire time covered by the government’s testimony. And though the duration of Turner’s possession may have been relatively brief, the circumstances surrounding it were cer *605 tainly not such that it can be said “the rational connection between defendant’s ‘possession’ and the probability that the defendant had knowledge of the source of the drugs would be remote * * *." Hernandez v. United States, 300 F.2d 114, 123 (9th Cir. 1962). Cf. United States v. Santore, 290 F.2d 51, 79, 82 (2d Cir. 1960).

We conclude that as to Turner the evidence was sufficient to establish all of the elements of the offense.

The instruction which the trial court gave as to the function of the section 174 inference followed the form found in Mathes & Devitt, Federal Jury Practice & Instructions, § 39.08 (1965). It is commonly given. Counsel did not object to it below and has not challenged it here. Nonetheless, it seems advisable to point out that this instruction, quite understandably, no longer states the jury’s functions in relation to the inference, as developed in recent decisions, as clearly as it might. Cf. United States v. Llanes, 374 F.2d 712, 716 (2d Cir. 1967); United States v. Reid, 347 F.2d 344, 345 (2d Cir. 1965). The instructions approved by the Supreme Court in United States v. Gainey, 380 U.S. 63, 69-70 , 85 S.Ct. 754 , 13 L.Ed.2d 658 (1965), modified in light of the differences in the statutes involved, furnishes a guide for an appropriate instruction on this subject.

It should also be noted that to avoid any possible Fifth Amendment problem “the better practice would be to instruct the jurors that they may draw the inference unless the evidence in the case provides a satisfactory explanation for the defendant’s [possession of the narcotic drugs], omitting any explicit reference to the statute itself in the charge.” 380 U.S. at 71 , 85 S.Ct. at 759 n. 7 (emphasis added).

Turner also contends that the trial court committed plain error in instructing the jury on the meaning of the word “conceal,” as used in the statute and indictment. We agree that the instruction was erroneous, but the defect did not affect Turner’s substantial rights. Rule 30, 52(b), Federal Rules of Criminal Procedure.

The instruction, quoted in the margin, 5 opens with a succinct statement of the term’s ordinary meaning: “to hide or keep from sight or view.” In the present case, no more was required. But the instruction continues with the statement that as used in section 174 “conceal” has a broader meaning. A theory of constructive concealment is then presented. Its substance is that since there is an affirmative duty to keep narcotic drugs *606 in a sealed container bearing revenue stamps, failure of the possessor of untaxed drugs to reveal the drugs to the tax collector “amounts to concealment within the meaning of [section 174], even though such narcotic drugs may not actually be hidden or kept from sight or view.”

None of the cases cited in Mathes & Devitt’s work in support of the instruction 6 suggests this interrelationship between 21 U.S.C. § 174 (1964) and the narcotic-taxing statutes 26 U.S.C. §§ 4701-4707 (1964). We have found none that do. 26 U.S.C. § 4704 (a) (1964) can be traced no farther back than the Act of February 4, 1919, 49 Stat. 1131 , or perhaps, considered more generally, to the Act of December 17, 1914, 38 Stat. 785 . The origins of 21 U.S.C. § 174 are found in the Act of February 9, 1909, 35 Stat. 614 . When Congress made it an offense to “conceal” narcotic drugs in 1909 it could hardly have had in mind mere failure to satisfy a tax obligation which did not exist until 1919, or 1914, at the earliest. 7

The instruction is objectionable for still another reason. It describes an offense — the sale of narcotic drugs other than in or from the original stamped package, 26 U.S.C. § 4704 (a) (1964) 8 — with which appellants were not charged, and informs the jury that “the absence of appropriate tax-paid stamps from narcotic drugs is prima facie evidence of violation of law by the person in whose possession the same may be found.” At best the recitation of these irrelevant statutory provisions must be both distracting and confusing to a jury. It may also prejudice the defendant in a jury’s eyes by revealing the defendant’s commission of another crime. 9

In the present case, however, we think these risks were minimal. Appellants did not contend that the conduct testified to by Chesley did not constitute concealment within the meaning of the statute and the indictment. Obviously that testimony disclosed concealment in the ordinary sense, for if the transaction testified to by the witness occurred, it was undeniable that appellants had taken elaborate steps to secrete the heroin until delivery. The defense was that the events testified to by the government witness simply had not occurred at all. Thus, as the case was presented to the jury, appellants either did not have possession of the drugs at all or they concealed the drugs in the ordinary sense of that term, which was accurately stated in the instruction. There was no middle ground. The constructive possession subsequently described in the instruction was not presented as an alternative by any possible interpretation of the evidence. It therefore could not have been the basis for the verdict. United States v. Monticallos, 349 F.2d 80 (2d Cir. 1965); cf. United Brotherhood of Carpenters, etc. v. United States, 330 U.S. 395, 408-409 , 67 S.Ct. 775 , 91 L.Ed. 973 (1947).

We agree, of course, that “when a false issue of magnitude sufficient to nullify proper consideration of the issues is inserted into a case, the proper admin *607 istration of justice is thwarted and a conviction so based cannot stand.” Michaud v. United States, 350 F.2d 131, 134 (10th Cir. 1965). But the issue raised by this instruction was not of that magnitude. It is nowhere reflected in the examination of the witnesses; it was subject to no comment by either side in closing arguments. As we have said, the contest occupied wholly different ground.

It is equally improbable that disclosure of appellant’s possible violation of the taxing statutes had any material impact upon the jury, in view of the essentially technical nature of the tax offense and its derivation from the same simple transaction as the offense charged. 10

Verdugo raises one additional issue relating to the trial. Agent Chesley testified that he had performed a “Marquis reagent” field test with the substance in the package and obtained a reaction indicating that it was a derivative of opium. Counsel for the parties stipulated that Mr. Meuron, a United States chemist “qualified as an expert witness in the field of narcotic drug analysis,” if called as a witness would testify that he had examined the substance and “formed the opinion” that the substance “was heroin.” Verdugo’s contention is that the trial judge invaded the province of the jury by instructing that heroin is a derivative of opium and therefore “a narcotic drug as defined by law.” 11

We have held that “an instruction * * * which assumes an admitted or uncontroverted fact, is not reversible error.” Lyons v. United States, 325 F.2d 370, 375 (9th Cir. 1963). Cf. Brown v. United States, 334 F.2d 488 (9th Cir. 1964) (Judge Duniway concurring). This is an a fortiori case. That heroin is an opium derivative was not simply uncontroverted, it is incontrovertible. Trotter v. United States, 359 F.2d 419 (2d Cir. 1966); Jordan v. United States, 345 F.2d 302, 304 (10th Cir. 1965); United States v. Pisano, 193 F.2d 355, 359-360 , 31 A.L.R.2d 409 (7th Cir. 1951); cf. Rivas v. United States, 368 F.2d 703, 712 (9th Cir. 1966). The court’s further instruction that an opium derivative is a “narcotic drug” is simply a statement of law, for this is the statutory definition. It was therefore proper to instruct the jury that heroin is a “narcotic drug.” The only issue for the jury was whether this was what the package contained. A later instruction, read in conjunction with the instruction to which Verdugo objects, left that issue to the jury. 12

*608 Verdugo was sentenced to fifteen years’ imprisonment. Turner was sentenced to five years, the minimum permitted by law, to run concurrently with a sentence imposed earlier by the State of California for another narcotics offense. Verdugo asserts that this wide disparity resulted from two errors in the sentencing process. 13 Both claims of error rest upon the use by the sentencing judge of a presentenee investigation report prepared by a federal probation officer. The district court ordered the presentence report made part of the record on appeal. Verdugo calls attention to the following portions of the report.

The report recites that a large quantity of heroin and a substantial sum of money were seized in Verdugo’s residence on October 1, 1964, and that the money included official advance funds paid “to five different defendants who were alleged to be trafficking in heroin for defendant Verdugo.” As noted later, prior to trial the heroin referred to was suppressed as evidence and the money was ordered returned to Verdugo on the ground their seizure violated Verdugo’s Fourth Amendment rights, and this reference to the suppressed evidence in the report is the basis for Verdugo’s second claim of error.

The report continues, “It was alleged that for many months prior to his arrest, defendant was the major source of narcotics in the Mission District of San Francisco, having as high as 15 to 20 people dealing in heroin for him at one time.” It states later, “though defendant has apparently never used narcotics, he is reputed to be one of the major sources of heroin in the Mission District of San Francisco and is alleged to have built up a large organization distributing heroin for him”; and further, “There appears to be no question whatsoever regarding defendant’s activities as a supplier of narcotics to a large number of people and no question that these activities were conducted purely on a profit motivated basis.”

Verdugo “is reported to always carry large sums of money on his person,” and it is noted that when found guilty he gave a “large sum” to his attorney in the courtroom for delivery to Mrs. Verdugo. Verdugo’s “continual possession of large sums of money” is said to be “rather significant” in view of Verdugo’s “long periods of unemployment.”

The report twice states that Verdugo “allegedly” hired Turner as his “gunman.” It is said that Verdugo threatened the life of the arresting officer and the undercover agent at the time of his arrest. From this premise it is concluded that Verdugo presents “a real physical danger to certain individuals whom he has already threatened. It is felt defendant is perfectly willing to carry out these threats and capable of doing so.”

The report concludes, “Though he would possibly not profit personally, it is felt society would be best protected if defendant would incur a substantial term of incarceration, in excess of the minimum five year sentence required.”

The government does not dispute Verdugo’s suggestion that the highly adverse recitations in the presentence report may have been of crucial significance in determining his sentence within the broad statutory range. 14

*609 Verdugo’s first claim of error is that the presentence report was not made available to him and to his counsel before sentence was imposed. He contends that his right “to make a statement in his own behalf and to present any information in mitigation of punishment” (Rule 32(a), Fed.R.Crim.P.) was of little value without knowledge of the allegations in the presentence report; and that his right to the effective aid of counsel at sentencing 15 was equally empty since counsel’s ignorance of these allegations precluded him from dealing with them directly and specifically. He argues that it is impossible to defend the fairness of a sentencing procedure in which allegations of the determinative facts were immunized from explanation, correction, or refutation by deliberate nondisclosure.

The appellant’s argument has force; and the authorities provide no ready answer. 16 However, since the entire presentence report is now part of the record and, for reasons which follow, we have concluded that Verdugo must be re-sentenced, 17 we need not decide whether in the circumstances of this case the critical factual allegations of the presentence report should have been disclosed to Verdugo or his counsel before sentence was imposed.

Verdugo’s second claim of error relating to the presentence report is that the inclusion in the report and consideration by the sentencing judge of information obtained from his home by unconstitutional search and seizure violated his rights under both the Fourth and Fifth Amendments. The relevant facts are as follows.

A complaint charging Verdugo with the July 28, 1964, transaction involving 2.695 grams (.0961 ounces) of heroin was filed with the United States Commissioner on September 30, 1964. A Commissioner’s warrant for Verdugo’s arrest was issued the same day. ■ Government agents arrested Verdugo and searched his residence the following day, seizing 371.465 grams (13.11 ounces) of heroin and $7,583 in currency.

A two-count indictment was returned November 18, 1964. The first count rested upon the July 28 transaction; the second count, charging Verdugo alone, on-concealment of the 371.465 grams of heroin seized on October 1.

Verdugo filed a motion for suppression of the 371.465 grams of heroin and the $7,583 as evidence, and for return of the money. The district court, after an evidentiary hearing, found that the search and seizure violated Verdugo’s Fourth Amendment rights and granted the motion. United States v. Verdugo, 240 F.Supp. 497 (N.D.Calif.1965).

The district court found that the officers went to Verdugo’s residence “to look for the contraband and to make an arrest in order to get the same.” 240 F.Supp. at 498 . The court rejected the officers’ testimony that they were “invited” into the home by Verdugo’s wife, and found that they “intruded themselves without her consent.” The court *610 pointed out that Verdugo was absent when the officers arrived. The officers made a preliminary search before stationing themselves in Verdugo’s home to await his return. They refused to permit Mrs. Verdugo to leave or to use the telephone. When Verdugo arrived he was arrested without being told of the charge. He was handcuffed to a chair to restrain his movements, and the search continued for two and a half hours thereafter. Both Mr. and Mrs. Verdugo were then taken to jail, although it does not appear that there was a warrant for Mrs. Verdugo’s arrest. The search continued for about two more hours after the Verdugos were taken away. Five to seven officers ransacked the Verdugo home, searching drawers, cabinets, and luggage, overturning furniture, removing covers from all of the house light switches, and punching holes in the wallboard. 240 F.Supp. at 499-500 . Visitors to the Verdugo home while the search was in progress were “herded together and subjected to the strict police control of the premises.” Id. at 501 . “In truth,” the court concluded, “the Verdugo home was converted into a police sub-station and was not the sanctuary which the Fourth Amendment commands it shall remain.” Id. at 501 (footnote omitted).

The court also noted that the officers had no search warrant, although “Verdugo’s activities had been the subject of investigation for at least two months before the federal agents chose to stage this siege of his home, admittedly in search of ‘stash.’ There was ample time to obtain a search warrant. No emergency existed and no explanation or excuse is offered .by the government for proceeding without a warrant.” Id. at 500 .

After entry of the suppression order, the second count of the indictment was dismissed on the government’s motion.

In Armpriester v. United States, 256 F.2d 294 (4th Cir. 1958), a government witness at presentence hearing testified that after his arrest Armpriester had made a statement admitting guilt. The statement was obtained during a period of detention violative of Rule 5(a), Federal Rules of Criminal Procedure, and therefore would have been inadmissible in a trial on the issue of guilt. Mallory v. United States, 354 U.S. 449 , 77 S.Ct. 1356 , 1 L.Ed.2d 1479 (1957). Judge Sobeloff, speaking for the court, made it unmistakably clear that if prejudice appeared, 18 resentencing would be required: “It is recognized that a court has wider latitude of inquiry in fixing the sentence than during a contest to decide an issue of guilt, [citations] Nevertheless, we would not condone the use of evidence obtained in breach of the law, even for the limited purposes of determining the sentence. The rationale of the Mallory case is that judicial proceedings shall stand or fall independently of evidence obtained in violation of Rule 5(a).” 256 F.2d at 297 .

Ours would seem an a fortiori case, for the evidence considered in sentencing Verdugo was obtained in violation of a constitutional prohibition, not merely a rule of procedure. Moreover, the exclusionary rule with which we are concerned is a part of the constitutional right, not merely a rule of evidence adopted in the exercise of a supervisory *611 power. Mapp v. Ohio, 367 U.S. 643 , 81 S.Ct. 1684 , 6 L.Ed.2d 1081 (1961).

Mapp firmly established the doctrine that the exclusionary rule is part of the constitutional right to be free of unreasonable search and seizure. The precise basis for the doctrine is less clear, and the ground which ultimately prevails may, in some circumstances, affect the propriety of use of illegally seized evidence in sentencing. We are satisfied, however, that exclusion is "required in this case upon any of the possible grounds for the rule.

The primary and least rigid basis for the exclusionary rule is that exclusion is required to deter the police from illegal searches and seizures.

In Linkletter v. Walker, 381 U.S. 618, 636-637 , 85 S.Ct. 1731, 1741 , 14 L.Ed.2d 601 (1965), the Court stated: “Mapp had as its prime purpose the enforcement of the Fourth Amendment through the inclusion of the exclusionary rule within its rights. This, it was found, was the only effective deterrent to lawless police action. Indeed, all of the cases since Wolf requiring the exclusion of illegal evidence have been based on the necessity for an effective deterrent to illegal police action.” Thus Mapp may be read as saying only “that the Fourth Amendment, reasonably construed, allows the Court to apply the exclusionary rule if it is deemed necessary to ensure compliance with the provisions of the amendment.” Landynski, Search and Seizure and the Supreme Court 78 (1966). So read, Mapp , may permit relaxation of the exclusionary rule when its enforcement would have no deterrent effect or the deterrent effect would be insubstantial. Cf. Terry v. State of Ohio, 392 U.S. 1, 13-16 , 88 S.Ct. 1868, 1875-1877 , 20 L.Ed.2d 889 (1968).

Assuming this, we would nonetheless conclude that exclusion was required in the circumstances of the present case.

There is undoubtedly a strong public interest in the imposition of a proper sentence — one based upon an accurate evaluation of the particular offender and designed to aid in his personal rehabilitation. The permissible scope of the sentencing judge’s inquiry is accordingly broad, and limitations are not lightly imposed either upon the kind of information the court may consider or the source from which it may be obtained. 19

But the use of illegally seized evidence at sentencing cannot always be justified by this simple generality. It cannot be supposed, for example, that the court could properly consider evidence illegally seized after conviction from the accused’s home by narcotics agents or by the probation officer in a zealous but misguided effort to furnish the court with full information for. sentencing. 20 Moreover, whenever it is held that the deterrent value of the exclusionary rule justifies the release of a guilty man, courts necessarily also surrender the opportunity of imposing sentence upon him — the loss of this opportunity is not regarded as too great a price for insuring observance of *612 Fourth Amendment restraints by law enforcement officers.

The incentive for illegal searches which would be created if use of the illegally seized evidence were permitted in the circumstances of this case is all too clear. The record reveals that the July 28 transaction occurred in the course of an enforcement program by agents of the Bureau of Narcotics in a particular area of San Francisco, extending over a period of several months. Agent Chesley himself participated in some ninety “buys” during a ten-week period. When the decision to search Verdugo’s home was made, the agents already had in their possession sufficient evidence to convict Verdugo of the July 28 transaction. They were not seeking additional evidence for that purpose. They hoped to locate a wholesale supply of heroin. As the district court found, the agents went to Verdugo’s home “to look for the contraband and to make an arrest to get the same.”

The incentive for the search was strong. The range of possible penalty was wide — five to twenty years. The length of Verdugo’s sentence would be quite different if it could be shown that Verdugo was involved in the narcotics traffic on a large scale rather than merely as the seller in a single small transaction.

\lf the fruits of the search could be used to enhance the sentence, the possibility that the evidence might be excluded at trial would be of little importance in view of the untainted evidence available to establish the July 28 offense. Unless the evidence were unavailable for sentence as well as conviction, the agents had nothing to lose by risking an unlawful search: if the motion to suppress were denied, Verdugo could be convicted of an additional offense; if it were granted, the sentence on the original charge could still be enhanced. 21

It might be suggested that police officers are unlikely to be concerned with the sentence ultimately imposed, and, therefore, that excluding evidence at the sentencing stage cannot serve as a substantial deterrent. But this cannot be said, even now, of “the highly specialized unit which deals with specific kinds of offenses, such as those associated with narcotics, which are very serious in nature, where the investigation task is difficult, and where offenders are likely to be recidivists. \ Here, there may, indeed, be a specific police objective of lengthy incarceration, since the specialized unit may consider premature release of the offender back into the community as making more difficult their job.” Ohlin & Remington, Sentencing Structure: Its Effect upon Systems for the Administration of Criminal Justice, 23 Law & Contemporary Problems, 494, 501 (1958). 22 And even if it were true that there is now no general consciousness of the potential utility of illegally seized evidence to enhance sentence, we could not ignore the fact that announcement of an exception to the exclusionary rule would inevitably produce it. 23

*613 We conclude that where, as here, the use of illegally seized evidence at sentencing would provide a substantial incentive for unconstitutional searches and seizures, that evidence should be disregarded by the sentencing judge. Verdugo must therefore be resentenced without consideration of such evidence. 24

As to Turner the judgment is affirmed; as to Verdugo the case is remanded for resentence.

. The indictment was drawn under 21 U.S.C. § 174 , which reads:

Whoever fraudulently or knowingly imports or brings any narcotic drug into the United States or any territory under its control or jurisdiction, contrary to law, or receives, conceals, buys, sells, or in any manner facilitates the transportation, concealment, or sale of any such narcotic drug after being imported or brought in, knowing the same to have been imported or brought into the United States contrary to law, or conspires to commit any of such acts in violation of the laws of the United States, shall be imprisoned not less than five or more than twenty years and, in addition, may be fined not more than $20,000. For a second or subsequent offense (as determined under section 7237 (c) of the Internal Revenue

. See note 2 on page 603.

*603 Code of 1954), the offender shall be imprisoned not less than ten or more than forty years and, in addition, may be fined not more than $20,000.

Whenever on trial for a violation of this section the defendant is shown to have or to have had possession of the narcotic drug, such possession shall be deemed sufficient evidence to authorize conviction unless the defendant explains the possession to the satisfaction of the jury.

2. Particularly pertinent are our decision in Chavez v. United States, 343 F.2d 85 (1965), and the decisions of the Second Circuit in United States v. Peeples, 377 F.2d 205 (1967), and United States v. Llanes, 374 F.2d 712 (1967), interpreting the second paragraph of § 174, and the decisions of the Supreme Court in United States v. Gainey, 380 U.S. 63 , 85 S.Ct. 754 , 13 L.Ed.2d 658 (1965), and United States v. Romano, 382 U.S. 136 , 86 S.Ct. 279 , 15 L.Ed.2d 210 (1965), interpreting other statutes providing for similar inferences.

. An explanation of possession “to the satisfaction of the jury,” as those words are used in the second paragraph of § 174, means any evidence, direct or circumstantial, which is sufficient to satisfy the jury that despite evidence of possession by the defendant the. government has failed to meet its burden of proof. Such a failure of proof may occur, despite proof of possession, with respect to any one of the essential elements of the § 174 offense.

In United States v. Llanes, 374 F.2d 712, 715 (2d Cir. 1967), Judge Friendly offers examples of exculpatory evidence with respect to each of the elements of the offense except that of illegal importation. A possible basis for evidence negating this clement of the offense is afforded by the provision of 21 U.S.C. § 513 authorizing importation “of any narcotic drug or drugs” for scientific purposes. Cf. Erwing v. United States, 323 F.2d 674 (9th Cir. 1963).

Llanes , as well as Chavez v. United States, 343 F.2d 85, 90 (9th Cir. 1965), and Griego v. United States, 298 F.2d 845, 848 (10th Cir. 1962), hold that testimony that the defendant did not know that the drugs found in his possession were illegally imported requires submission of the issue of knowledge of unlawful importation to the jury for determination under the standard of reasonable doubt. Cf. United States v. Christmann, 298 F.2d 651, 653 (2d Cir. 1962), which holds that the defendant’s testimony that she thought the package which she illegally imported contained “essence of perfume” rather than heroin, made satisfaction of the requirement that the physical act specified in the statute be done “knowingly” an issue of fact for the jury.

. Turner points out that he moved for judgment of acquittal under rule 29(a), Fed.R.Crim.P., at the close of the government’s case, and contends that testimony subsequently introduced as part of his own case should not be considered in reviewing the denial of this motion, citing Frankln v. United States, 117 U.S.App.D.C. 331 , 330 F.2d 205, 208 (1964), which rests upon Cephus v. United States, 117 U.S.App.D.C. 15 , 324 F.2d 893 (1963). These cases hold the waiver doctrine inapplicable where the inculpating testimony is that of a co-defendant. This circuit has followed the waiver rule generally, see decisions from this and other circuits cited with approval in United States v. Calderon, 348 U.S. 160 , 164 n. 1, 75 S.Ct. 186 , 99 L.Ed. 202 (1954); see also Benchwick v. United States, 297 F.2d 330, 335 (9th Cir. 1961); Maulding v. United States, 257 F.2d 56, 58 , 17 Alaska 592 (9th Cir. 1958). Since we do not rely upon Verdugo’s testimony, we need not consider the exception suggested in Franklin and Cephus .

. The instruction, taken from Mathes & Devitt, Federal Jury Practice & Instructions, § 39.07 (1965), reads:

Although the verb “conceal” ordinarily means to hide or keep from sight or view, the expression as used in the statute and the indictment here carries a broader meaning. The law imposes an internal revenue tax upon all legitimate narcotic drugs and provides that revenue stamps evidencing payment of the tax “shall be so affixed to the bottle or other container as to securely seal the stopper, covering, or wrapper thereof.” It is unlawful “for any person to purchase, .sell, dispense, or distribute narcotic drugs except in the original stamped package or from the original stamped package; the absence of appropriate tax-paid stamps from narcotic drugs is prima facie evidence of violation of law by the person in whose possession the same may be found,” unless the person possessing the narcotic drugs has obtained them from a registered dealer, such as a pharmacist, upon prescription issued for legitimate medical uses by a physician or other registered and licensed person. Since the law imposes upon every person possessing a narcotic drug (other than upon legitimate medical prescription) the affirmative duty to keep the narcotic drug in a container bearing revenue stamps evidencing payment of the tax, the wilful failure of a person who is in actual or constructive possession of any untaxed narcotic drug (other than upon legitimate medical prescription) to reveal to some Internal Revenue official the existence of such narcotic drug, amounts to a concealment within the meaning of the statute, even though such narcotic drug may not actually be hidden or kept from sight or view.

. Hyche v. United States, 286 F.2d 248 (5th Cir. 1961); Corey v. United States, 305 F.2d 232, 236 (9th Cir. 1962); United States v. Mathies, 203 F.Supp. 797 (W.D.Pa.1962).

. It may also be noted that cases arising under 26 U.S.C. § 7206 (4) (1964) and its predecessors, making it an offense to “conceal” non-taxpaid liquor, give the term its ordinary meaning, United States v. Davis, 369 F.2d 775, 779 (4th Cir. 1966); Turner v. United States, 192 F.2d 41 (4th Cir. 1951); see also United States v. Shapiro, 113 F.2d 891, 892-893 , 130 A.L.R. 147 (2d Cir. 1940).

. 26 U.S.C. § 4704 (a) provides:

It shall be unlawful for any person to purchase, sell, dispense, or distribute narcotic drugs except in the original stamped package or from the original stamped package; and the absence of appropriate tax-paid stamps from narcotic drugs shall be prima facie evidence of a violation of this subsection by the person in whose possession the same may be found.

. Other possibly injurious consequences of the instruction are suggested by Turner, but seem to us too remote and speculative to merit serious consideration.

. This case is not like Polansky v. United States, 332 F.2d 233 (1st Cir. 1964), relied upon by Turner, in which the jury was instructed that the defendant was charged with another offense of which she had in fact been acquitted.

Turner also relies upon United States v. Harman, 323 F.2d 650, 651 (4th Cir. 1963), where the error “consisted in failing to instruct the jury as to the law applicable to the respective counts, and in instructing the jury as to an inapplicable presumption.” Keversal followed upon the appellate court’s conclusion that “on the whole record substantial rights of the defendant were affected.” The opinion does not disclose the particular circumstances of the case. In any event, we have reached the conclusion that on the present record Turner’s substantial rights were not impaired.

. The instruction read:

The term “narcotic drug” as used in the statute just read, means “Opium or any compound or derivative or preparation of opium.”

Heroin is a derivative of morphine, and morphine and morphine hydrochloride are both products of opium. Heroin is therefore a narcotic drug as defined by law.

. The instruction read:

You will, of course, first ascertain whether or not the substance in question is in fact a narcotic drug, as alleged; and in so doing you will consider all evidence in the case which may aid determination of that issue, including the testimony of a chemist or other witness, or a stipulation, as in this case, as to what the chemist would have testified to had one been called as a witness, either to support or dispute the allegation that the substance in question is a narcotic drug, as alleged.

Thus the trial court left to the jury the only issue of “fact” presenting a question *608 of credibility for the jury. Brown v. United States, 334 F.2d 488, 500-501 (9th Cir. 1964) (Judge Duniway concurring).

. Verdugo’s further contention that the difference in the two sentences “is ‘so unjustifiable as to be violative of due process’ ” (Schneider v. Rusk, 377 U.S. 163, 168 , 84 S.Ct. 1187, 1190 , 12 L.Ed.2d 218 (1964)) does not warrant separate discussion.

. The impact of the presentence report is not limited to its effect upon the sentence. Following sentencing the report accompanies the prisoner to the institution where its contents are used “(2) to assist Bureau of Prisons institutions in their classification and treatment programs and also in their release planning, (3) to furnish the Board of Parole with information pertinent to its consideration of parole, (4) to aid the probation officer in his rehabilitative efforts during probation and parole supervision, and (5) to serve as a source of pertinent information for systematic research” (footnote *609 omitted). Administrative Office of the U.S. Courts, Pub.No. 103, The Presentence Investigation Report 1 (1965) ; Chappel, Federal Parole, 37 F.R.D. 207 , 210-211 (1964); Parsons, Aids in Sentencing, 35 F.R.D. 423 , 429 (1964).

. Mempa v. Rhay, 389 U.S. 128, 134 , 88 S.Ct. 254 , 19 L.Ed.2d 336 (1967); Townsend v. Burke, 334 U.S. 736 , 68 S.Ct. 1252 , 92 L.Ed. 1690 (1948); Roeth v. United States, 380 F.2d 755, 756 (5th Cir. 1967); Leach v. United States, 118 U.S.App.D.C. 197 , 199, 334 F.2d 945, 947 (D.C.Cir. 1964).

Subsequent to Verdugo’s sentencing, Rule 32(a) was amended by adding a provision, among others, that counsel shall be given an opportunity “to speak on behalf of the defendant.”

. We reserved the question of right to access to the presentenee report in Pearce v. United States, 262 F.2d 662, 664 (9th Cir. 1958).

. It is also unnecessary to consider whether Verdugo’s claim should be rejected because his counsel failed to request the trial judge to disclose the report after having been refused access to the report by the probation officer. Cf. Roeth v. United States, 380 F.2d 755, 757 (5th Cir. 1967).

. The court found no .possibility that reference to the statement could have influenced the sentence since the content of the statement was adduced independently. 256 F.2d at 297 . We cannot avoid the question of the propriety of considering this evidence in sentencing Verdugo on this ground. It appeared from the evidence at trial that Verdugo played the primary role in the July 28 transaction. The presentence reports reflected other differences between the two men, some favorable to Turner, others to Verdugo. However, the marked difference between the two was that Verdugo was said to be a large scale dealer in narcotics for profit. Aside from rumors, which the presentence report properly labeled as such, the basic support for this charge was the discovery of the wholesale quantity of heroin and the official funds disbursed in four other narcotics buys in the October 1 search of Verdugo’s premises.

. Williams v. People of State of New York, 337 U.S. 241 , 69 S.Ct. 1079 , 93 L.Ed. 1337 (1949) ; Davis v. United States, 376 F.2d 535, 538 (5th Cir. 1967) ; Beufve v. United States, 374 F.2d 123 (5th Cir. 1967) ; United States v. Doyle, 348 F.2d 715, 721 (2d Cir. 1965) ; United States v. Magliano, 336 F.2d 817, 822 (4th Cir. 1964) ; Application of Hodge, 262 F.2d 778, 782 (9th Cir. 1958) ; Taylor v. United States, 179 F.2d 640, 642-643 (9th Cir. 1950) ; Cf. Marano v. United States, 374 F.2d 583, 585 (1st Cir. 1967) ; Armpriester v. United States, 256 F.2d 294, 297 (4th Cir. 1958).

. The holding of Camara v. Municipal Court, 387 U.S. 523 , 87 S.Ct. 1727 , 18 L. Ed.2d 930 (1967), that the Fourth Amendment must be complied with in municipal fire, health, and housing inspection programs seems inconsistent with the suggestion (Hincks, In Opposition to Rule 34(c) (2), Proposed Federal Rules of Criminal Procedure, 8 Fed.Prob., Oct.Dec. 3.7 (1944)) that constitutional limitations are inapplicable at the sentencing stage because sentencing is essentially an effort to deal with a “social problem.” See also Martin v. United States, 183 F.2d 436, 439 (4th Cir. 1950), holding that the Fourth Amendment protection against unreasonable searches extends to the home of a probationer.

. Quite different considerations would apply if the object of the search were to obtain evidence to support a single charge on which the defendant was later convicted. If the additional evidence was necessary to obtain any conviction at all, the danger of exclusion at trial would afford a substantial deterrent to an illegal search. If the additional evidence was not required for conviction, both the deterrent effect of the exclusion of illegally seized evidence of the same offense at sentencing and the incentive to conduct legal searches to obtain such evidence would appear to be minimal.

. See Caplan, Book Review, 80 Harv.L.Rev. 484, 488 (1966); Tiffany, McIntyre & Rotenberg, Detection of Crime 137-138 (1967).

. Cf. Allen, Federalism and the Fourth Amendment: A Requiem for Wolf, The Supreme Court Review 1, 36 (1961):

Some states sought to avoid the heavy costs involved in complete acceptance or rejection of the exclusionary rule by holding the rule applicable only to certain categories of offenses. The consequences were predictable. The police, being of a pragmatic turn, tended to interpret the withdrawal of the rule in *613 given offense categories as a license to proceed in those areas without legal restraint. [Footnotes omitted.]

. We need not decide whether the doctrine of waiver or estoppel applied in Walder v. United States, 347 U.S. 62 , 74 S.Ct. 354 , 98 L.Ed. 503 (1954), is applicable at sentencing. The illegally seized evidence was not offered solely in rebuttal of an initial contrary factual showing by Verdugo, as is sometimes made by a defendant at sentencing, for example in support of a plea for probation. Agnello v. United States, 269 U.S. 20 , 46 S.Ct. 4 , 70 L.Ed. 145 (1925) ; Lee v. United States, 368 F.2d 834 (D.C.Cir. 1966) ; Inge v. United States, 123 U.S.App.D.C. 6 , 356 F.2d 345, 349-50 (1966) ; White v. United States, 121 U.S.App.D.C. 287 , 349 F.2d 965 (1965) ; Johnson v. United States, 120 U.S.App.D.C. 69 , 344 F.2d 163 (1964) ; United States v. Beno, 324 F.2d 582, 588 (2d Cir. 1963).