We must decide whether a California death row inmate is entitled to discovery before filing a federal habeas petition.

I

Arthur Calderon, Warden of the California State Prison at San Quentin, petitions this court for a writ of mandamus (1) to vacate the discovery order issued by the district court upon the request of Real Party in Interest Robert Henry Nicolaus, and (2) to prohibit the issuance of any discovery orders until Nicolaus files a fully exhausted habeas corpus petition.

Nicolaus murdered his three children (ages two, five, and seven) in May 1964. He was convicted of three counts of first degree murder and sentenced to death, but the California Supreme Court reduced his convictions to second degree murder and the State released him on parole in August 1977.

In February 1985, Nicolaus killed his ex-wife, who identified him as her killer before her death. Nicolaus fled California, but the FBI arrested him in Pennsylvania in July 1985. A Santa Clara jury convicted Nicolaus of one count of first degree murder and returned a sentence of death in March 1987. The California Supreme Court affirmed the death sentence in October 1991 and denied his state habeas petition in November 1991. The U.S. Supreme Court denied certiorari in June 1992. Nicolaus v. California, 505 U.S. 1224 , 112 S.Ct. 3040 , 120 L.Ed.2d 908 (1992).

In September 1992, the district court granted Nicolaus’ motion for a stay of execution, and in April 1993 the court appointed counsel for Nicolaus’ federal habeas appeal. To date, Nicolaus has not filed a petition.

In October 1995, counsel for Nicolaus filed a discovery motion to serve subpoenas on the Sacramento District Attorney’s Office and the Sacramento Police Department, seeking access to all documents pertaining to Nico-laus’ ease. 1 Nicolaus maintains that the FBI has not given him all the documents relevant to his case, and he hopes to find some of these FBI documents in the files of the Sacramento authorities.

On December 8, 1995, without holding a héaring and without presenting any explanation of “good cause,” the district court granted Nicolaus’ motion to serve the subpoenas. The district court denied Calderon’s request for a stay of the discovery order pending application to this court for a writ of mandamus. Calderon filed a timely petition with an emergency motion for a stay of the discovery order. We granted the stay on April 5, 1996.

II

Rule 6(a) of the Federal Rules Governing Section 2254 Cases allows parties to engage in discovery in the discretion of the court and “for good cause shown.” The rule provides that a “party shall be entitled to invoke the processes of discovery available under the Federal Rules of Civil Procedure if, and to the extent that, the judge in the exercise of his discretion and for good cause shown grants leave to do so, but not otherwise.” See Campbell v. Blodgett, 982 F.2d 1356, 1358 (9th Cir.1993) (citation omitted) (“there simply is no federal right, constitutional or otherwise, to discovery in habeas proceedings as a general matter”).

Rule 6(a) is silent as to whether a district court may order discovery before a petition has been filed. The Advisory Committee Note states:

A

On April 24,1996, President Clinton signed into law the Antiterrorism and Effective Death Penalty Act of 1996 (the “Act”), Pub.L. No. 104-132, 110 Stat. 1217. As a threshold matter, we must consider what impact, if any, the Act may have on Calderon’s mandamus petition.

Title I of the Act, which amends Chapter 153 of Title 28 of the United States Code, applies to all federal habeas challenges to state criminal judgments. See Felker v. Turpin, — U.S. —, 116 S.Ct. 2333 , 135 L.Ed.2d 827 (1996) (upholding Title I of the Act as constitutional). Since the Act is silent as to the date of effectiveness that attaches to these provisions, courts reviewing Chapter 153 must determine whether the provision at issue is substantive (presumption against ret-roactivity applies) or procedural (presumption in favor of retroactivity applies). See Chenault v. U.S. Postal Service, 37 F.3d 535, 538 (9th Cir.1994) (interpreting Landgraf v. USI Film Prods., 511 U.S. 244 , 114 S.Ct. 1483 , 128 L.Ed.2d 229 (1994)). However, we need not decide whether Chapter 153 applies to this petition for mandamus because the Chapter’s provisions do not deal with pre-petition discovery. The provisions mainly address how courts should treat allegations once they have already been outlined in a petition.

The Act adds Chapter 154 to Title 28 of the United States Code. This new Chapter contains additional provisions applicable to habeas review of state death penalty judgments in states that comply with certain conditions. Although Chapter 154 applies to cases pending on or after the date of enactment, the United States District Court for the Northern District of California has enjoined Calderon from asserting that California is entitled to the benefits of the provisions of Chapter 154 “in any state or federal proceeding involving any prisoner under sentence of death by the State of California.” Ashmus v. Calderon, 935 F.Supp. 1048 (N.D.Cal. 1996) (Henderson, C.J.), calendared for appeal, No. 96-16141 (9th Cir. Sept. 18, 1996); see Calderon v. Ashmus, No. 96-16141 (9th Cir. June 20, 1996) (denying emergency motion for stay of injunctive relief). In any ease, nothing in Chapter 154 deals directly with discovery, let alone pre-petition discovery under Rule 6. Accordingly, we need not consider the applicability of the Act.

B

We now consider the merits of Calderon’s petition. In determining whether to issue a writ of mandamus, we balance the following five factors (“the Bauman factors”):

In re Cement Antitrust Litig., 688 F.2d 1297, 1301 (9th Cir.1982) (citing Bauman v. U.S. Dist. Ct., 557 F.2d 650, 654-55 (9th Cir.1977)), aff 'd sub nom. Arizona v. U.S. Dist. Ct., 459 U.S. 1191 , 103 S.Ct. 1173 , 75 L.Ed.2d 425 (1983); see 28 U.S.C. § 1651 . Although all five factors need not be satisfied, “it is clear that the third factor, the existence of clear error as a matter of law, is dispositive.” Executive Software North Am., Inc. v. U.S. Dist. Ct., 24 F.3d 1545 , 1551 (9th Cir.1994) (citations omitted). 2 See generally In re de *1106 merit, 688 F.2d at 1301 (“all of the guidelines are unlikely to be met in any one case” and “the guidelines serve only as a useful starting point”).

1

Since the third Bauman factor can be dispositive, we begin by considering whether the district court clearly erred as a matter of law.

We conclude that pre-petition discovery is impermissible for at least four reasons. First, a prisoner must outline factual allegations in a petition before the district court will be able to determine the propriety of discovery. As the Supreme Court stated in Harris v. Nelson, 394 U.S. 286 , 89 S.Ct. 1082 , 22 L.Ed.2d 281 (1969), which established the basis for Rule 6: “[I]n appropriate circumstances, a district court, confronted by a petition for habeas corpus which establishes a prima facie case for relief, may use or authorize the use of suitable discovery procedures .... ” Id. at 290 , 89 S.Ct. at 1086 (emphasis added); see also Mayberry v. Petsock, 821 F.2d 179, 185 (3d Cir.) (citation omitted) (“Unless the petition itself passes scrutiny, there would be no basis to require the state to respond to discovery requests.”), cert. denied, 484 U.S. 946 , 108 S.Ct. 336 , 98 L.Ed.2d 362 (1987).

Second, any right to federal discovery presupposes the presentation of an unexhausted federal claim, because a federal habeas petitioner is required to exhaust available state remedies as to each of the grounds raised in the petition. See Duncan v. Henry, — U.S. —, —, 115 S.Ct. 887, 888 , 130 L.Ed.2d 865 (1995) (per curiam); see also Keeney v. Tamayo-Reyes, 504 U.S. 1, 9 , 112 S.Ct. 1715, 1719-20 , 118 L.Ed.2d 318 (1992) (“[t]he state court is the appropriate forum for resolution of factual issues in the first instance, and creating incentives for the deferral of fact-finding to later federal-court proceedings can only degrade the accuracy and efficiency of judicial proceedings”). Here, it is undisputed that Nicolaus has not sought the desired discovery from the California state court.

Third, Rule 6 is limited to “the processes of discovery available under the Federal Rules of Civil Procedure” and, with one inapplicable exception, the Federal Rules of Civil Procedure do not permit pre-complaint discovery. The exception arises when a party can show the need to perpetuate testimony that may not be available later. Fed. R.Civ.P. 27. Here, Nicolaus does not contend that his discovery request qualifies for this exception.

Fourth, courts should not allow prisoners to use federal discovery for fishing expeditions to investigate mere speculation. See Ward v. Whitley, 21 F.3d 1355, 1367 (5th Cir.1994) (footnotes omitted) (“federal habeas court must allow discovery and an evidentia-ry hearing only where a factual dispute, if resolved in the petitioner’s favor, would entitle him to relief.... Conclusory allegations are not enough to warrant discovery under Rule 6 ...; the petitioner must set forth specific allegations of fact. Rule 6 ... does not authorize fishing expeditions.”), cert. denied, — U.S. —, 115 S.Ct. 1257 , 131 L.Ed.2d 137 (1995); United States ex rel. Nunes v. Nelson, 467 F.2d 1380, 1380 (9th Cir.1972) (state prisoner “is not entitled to a discovery order to aid in the preparation of some future habeas corpus petition”); Aubut v. State of Maine, 431 F.2d 688, 689 (1st Cir.1970) (“Habeas corpus is not a general form of relief for those who seek to explore their case in search of its existence.”). Nico-laus’ eligibility for discovery is especially questionable because the prisoners in Ward, Nunes, and Aubut at least filed a federal habeas petition. If the ambiguous allegations of these prisoners were insufficient to justify discovery, then certainly the utter absence of any specific allegations should preclude discovery.

In sum, we hold that the district court clearly erred in granting Nicolaus’ discovery *1107 request before Nicolaus presented specific allegations in the form of a verified petition.

In so holding, we reject Nicolaus’ assertion that the “cause and prejudice” test, which must be met by prisoners who attempt to file a successive federal habeas petition that raises new claims, counsels in favor of generous pre-petition discovery. See McCleskey v. Zant, 499 U.S. 467, 498 , 111 S.Ct. 1454, 1470, 1472 , 113 L.Ed.2d 517 (1991) (“petitioner must conduct a reasonable and diligent investigation aimed at including all relevant claims and grounds for relief in the first federal habeas petition”); Brown v. Vasquez, 952 F.2d 1164, 1167 (9th Cir.) (habeas petitioner “must assert all possible violations of his constitutional rights in his initial application or run the risk of losing what might be a viable claim”), cert. denied, 503 U.S. 1011 , 112 S.Ct. 1778 , 118 L.Ed.2d 435 (1992). This argument is a thinly veiled attempt to justify fishing expeditions before the filing of first petitions. The rationale offered by Nicolaus would apply to every potential habeas petitioner, thus creating an exception that would swallow the exhaustion rule. See In re Parker, 49 F.3d 204, 213 (6th Cir.1995) (“there is nothing in McCleskey , in McFarland, or in [ 21 U.S.C. § 848 (q)(4)(B) ], that indicates that federal courts may intervene to prevent execution for an indefinite period to assist in [the preparation of the first federal habeas petition]”).

Prisoners, such as Nicolaus, who come to federal court after having been denied habeas relief by the highest court of a state, may file a federal habeas petition that raises the same issues contained in then-state habeas proceedings. Here, Nicolaus could have done that, but has not. 3 In his state habeas proceedings, Nicolaus alleged juror misconduct, erroneous penalty instructions, and improper denial of separate guilt and penalty phase juries. Because Nicolaus exhausted these claims in state court, he could simply file a federal habeas petition raising these issues. In short, if Nicolaus wishes to allege formally that the FBI has withheld documents that he believes may tend to exonerate him, he should first bring such an unexhausted claim before the California state court.

Since the district court clearly erred in permitting discovery before the petition for writ of habeas corpus had been filed, Calderon has satisfied the third Bauman factor.

2

We also conclude that the remaining Bau-man factors weigh in favor of issuing the writ.

The first factor is satisfied because Calderon could not have directly appealed the district court’s discovery order. A petition for mandamus is the appropriate means to challenge such an order. Nicolaus does not challenge this conclusion.

The second factor is satisfied because once the state complies with the discovery order, the damage will be done — i.e., Nicolaus will have succeeded in delaying his execution by engaging in a comprehensive search through the government’s files without having made any specific allegations. 4 See In re Blodgett, 502 U.S. 236, 239 , 112 S.Ct. 674, 676 , 116 L.Ed.2d 669 (1992) (citing McCleskey, 499 U.S. at 489-93 , 111 S.Ct. at 1468-69 ) (stressing state’s “sovereign power to enforce the criminal law, an interest we found of great weight in McCleskey when discussing the importance of finality in the context of federal habeas corpus proceedings”).

The fourth factor also weighs in favor of issuance of the writ. Because district *1108 courts do not publish discovery orders, it is not easy to ascertain whether district courts repeatedly order pre-petition discovery. However, there is at least one other case pending before this court that involves the issue presented here, and we take judicial notice of these proceedings. See Calderon v. U.S. Dist. Ct. (Hill), No. 96-70039 (9th Cir. submission deferred). In the transcript of the Hill hearing, Judge Claudia Wilken stated: “I believe that pre-petition discovery is allowable and none of the orders allowing it has been published, but that’s not, I suppose, precedential authority. They have been ordered in other eases, and I can order it in this case as well.” Transcript of Proceedings Before Hon. Claudia Wilken, Hill v. Calderon, No. C94-0641, at 4 (N.D.Cal. Dec. 8, 1996). Judge Wilken’s statement supports the conclusion that pre-petition discovery may be an oft repeated error committed by the district courts.

Finally, the fifth factor weighs in favor of issuance of the writ because both parties recognize that this mandamus petition presents a legal issue of first impression.

Ill

In sum, all five Bauman factors weigh in favor of granting Calderon’s petition for a writ of mandamus. Accordingly, we grant the petition for a writ of mandamus (1) to vacate the discovery order issued by the district court, and (2) to prohibit the issuance of any discovery orders until Nicolaus files a federal petition for writ of habeas corpus.

PETITION GRANTED.

. Nicolaus has not sought this discovery from the California state courts.

. In addition, this court has held that mere error (versus clear error) may suffice:

In re Cement, 688 F.2d at 1307 (footnote- omitted).

. Unlike non-capital prisoners who initiate habe-as proceedings by filing a petition for a writ of habeas corpus, capital prisoners commence federal habeas proceedings by filing a request for appointment of counsel. McFarland v. Scott, - U.S. -, 114 S.Ct. 2568 , 129 L.Ed.2d 666 (1994).

. Nicolaus makes much of the fact that Calderon does not officially represent the two agencies that are the subjects of Nicolaus' two subpoenas: the Sacramento District Attorney’s Office and the Sacramento Police Department. Nicolaus relies on this fact for his argument that Calderon cannot be irreparably harmed by the discovery. This argument lacks merit because Calderon, as representative of the State of California, certainly can be damaged and prejudiced by any attempt to delay the state-sanctioned execution date or to bypass the state’s habeas procedures (with respect to original factfinding).