In this appeal from convictions by a jury for violation of the antitrust laws and sentences imposing fines, the defendant corporations make various contentions. We address ourselves to one contention and affirm.

Appellants contend that the per se rule as to price-fixing, i. e., that price-fixing is per se a violation of the antitrust laws and that the test of reasonableness has no application, is in substance the creation of a conclusive presumption and denies them due process in a criminal trial.

The use of presumptions in criminal law is limited by considerations of due process. Rebuttable presumptions which are arbitrary or irrational deny due process. A rebuttable presumption will be regarded as irrational and arbitrary unless it can be said with substantial assurance that the presumed fact is more likely than not to flow from the proved fact on which it is made to depend. Leary v. United States, 395 U.S. 6 , 89 S.Ct. 1532 , 23 L.Ed.2d 57 (1969); cf. United States v. Romano, 382 U.S. 136 , 86 S.Ct. 279 , 15 L.Ed.2d 210 (1965); United States v. Gainey, 380 U.S. 63 , 85 S.Ct. 754 , 13 L.Ed.2d 658 (1965); Tot v. United States, 319 U.S. 463 , 63 S.Ct. 1241 , 87 L.Ed. 1519 (1943). And since the accused is presumed innocent, he has the right to have each element of the crime charged submitted to the jury. Conclusive presumptions may not operate to deny this right. Morissette v. United States, 342 U.S. 246 , 72 S.Ct. 240 , 96 L.Ed. 288 (1952) . 1

Appellants’ contention that the per se rule constitutes an unconstitutional conclusive presumption misunderstands the Sherman Act. The Act, in part, broadly provides that “[e]very contract, combination ... or conspiracy in restraint of trade or commerce among the several States ... is declared to be illegal.” 15 U.S.C. § 1 , Act of July 2, 1890, ch. 647, 26 Stat. 209 .

In Standard Oil Co. v. United States, 221 U.S. 1, 60-68 , 31 S.Ct. 502 , 55 L.Ed. 619 (1911), and American Tobacco Co. v. United States, 221 U.S. 106 , 31 S.Ct. 632 , 55 L.Ed. 663 (1911), both civil cases, the Supreme Court interpreted the statute and spelled out the “Rule of Reason” as a limitation on the broad language of the Sherman Act, — i.e., that only unreasonable acts in restraint of trade and commerce were within the ambit of the statute.

In so doing, the Court disclaimed that it was changing the law as it existed in *51 1911. In United States v. American Tobacco Co., supra, the Court stated:

In 1927 the Court decided United States v. Trenton Potteries Company, 273 U.S. 392 , 47 S.Ct. 377 , 71 L.Ed. 700 . It sustained a criminal conviction for violation of the Sherman Act by price-fixing. The Court reviewed its antitrust holdings both before and after the Standard Oil and American Tobacco Co., supra. The Court concluded that price-fixing, in the cases decided both before and after Standard Oil and American Tobacco, had been held to be a per se violation of the Sherman Act without consideration of the rule of reasonableness. The Court, citing Thomsen v. Cayser, 243 U.S. 66, 84 , 37 S.Ct. 353 , 61 L.Ed. 597 and footnoting numerous lower court cases, pointed out that “the Standard Oil and Tobacco cases did not overrule the earlier cases” which held price-fixing to be illegal per se. 273 U.S. at 400 , 47 S.Ct. at 380 .

In United States v. Socony-Vacuum Oil Co. Inc., 310 U.S. 150 , 60 S.Ct. 811 , 84 L.Ed. 1129 (1940), a criminal case, the Court again reviewed its decisions on price-fixing. It stated :

*52 Thus the Court has interpreted a broad and inclusive statute, and since the earliest days of the Act, has enunciated two distinct rules of substantive law: (1) certain classes of conduct, such as price-fixing, are, without more, prohibited by the Act; (2) restraints upon trade or commerce which do not fit into any of these classes are prohibited only when unreasonable. The first rule, in light of the second, defines certain classes of pernicious conduct as unreasonable. Roughly restated, the per se rule establishes a conclusive presumption that certain types of conduct are unreasonable. See, Northern Pac. Ry. Co. v. United States, 356 U.S. 1, 5 , 78 S.Ct. 514 , 2 L.Ed.2d 545 (1958). This restatement, however, is no more than a pedagogic instrument, since the substantive rules of antitrust are no more rules of evidence than the substantive rules of any legal area.

Morissette, swpra, is inapposite. The per se rule does not operate to deny a jury decision as to an element of the crime charged, since “unreasonableness” is an element of the crime only when no per se violation has occurred. To put it differently “reasonableness” must be viewed as a legal term, and not in its ordinary sense. When the Court describes conduct as per se unreasonable, they do no more than circumscribe the definition of “reasonableness.”

While the appellants deserve credit for their ingenious and novel attempt to trap the Court in its own rhetoric, their contention that the per se rule should be set aside must be, and is rejected. The per se rule does not establish a presumption. It is not even a rule of evidence.

We have reviewed the appellants’ other contentions, including their attack on the sufficiency of the evidence and the correctness of the instructions and find no error.

The judgments are affirmed.

. The standard in non-criminal cases is somewhat different. Conclusive presumptions which result in arbitrary classifications are deemed invalid. Schlesinger v. Wisconsin, 270 U.S. 230 , 46 S.Ct. 260 , 70 L.Ed. 557 (1926). The legislature may not employ conclusive presumptions to legislate a fact which is at odds with actualities. Heiner v. Donnan, 285 U.S. 312 , 52 S.Ct. 358 , 76 L.Ed. 772 (1932).

. The latest Supreme Court case considering the per se rule is United States v. Topco Associates, Inc., 404 U.S. 596 , 92 S.Ct. 1126, 31 L.Ed.2d 515 (72), a civil case, involving allocation of territories, The ease upholds the allocation as a per se violation, but is not otherwise pertinent.