concurring.
I fully agree with the majority opinion’s conclusion that mandamus should not issue to require Judge Christian to convene an investigatory grand jury in the Virgin Islands. I write separately because I believe that there are additional considerations which buttress the result reached by the majority.
My analysis of Rules 6 and 7 of the Federal Rules of Criminal Procedure leaves no doubt in my mind that these Rules provide no authority for the District Court of the Virgin Islands to convene an investigatory grand jury. Moreover, even if we had concluded that Rules 6 and 7 provided the authority claimed by the government, I would not issue the writ of mandamus because the government has failed to demonstrate that it had a “clear and indisputable” right to the issuance of such a writ.
I.
In its petition to this court for a writ of mandamus, the government has asserted that Federal Rule of Criminal Procedure 6(a) authorizes the use of an investigatory grand jury in the Virgin Islands, a grand jury which can only investigate violations of federal law, but cannot indict. The government has not challenged the requirement that all offenses in the Virgin Islands must be prosecuted by information rather than by indictment. Instead the government has argued that this requirement — for prosecution by information — does not prevent the summoning of a grand jury for investigatory purposes only.
As Judge Adams has observed in the majority opinion, the government’s argument, made over a period of time, has shifted gears. Originally, the government sought to convince Chief Judge Christian to convene a special investigatory grand jury under the authority of 18 U.S.C. § 3331(a) (1976). It was the government’s position that this statute authorized the summoning of a grand jury to investigate “violations of federal law, including federal antitrust law, *904in the importation, wholesale and retail sale of liquor in the United States Virgin Islands.” (Letter of Justice Department addressed to Chief Judge Christian dated April 28, 1980.)
In response to that letter, Chief Judge Christian expressed his belief that the phrase “district court” used in § 3331(a) referred only to an Article III district court, and not to the District Court of the Virgin Islands, which is a territorial court created by Congress pursuant to Article IV, Section 3 of the Constitution. See United States v. George, 625 F.2d 1081, 1088-89 (3d Cir. 1980). Judge Christian then observed that Section 25 of the Revised Organic Act of the Virgin Islands, see 48 U.S.C. § 1615, and Rule 54(a) of the Federal Rules of Criminal Procedure both provide that all prosecutions in the District Court of the Virgin Islands (except as otherwise required by local law) shall be prosecuted by information. Finally, he observed that a grand jury never had been convened in the Virgin Islands and that the procedural machinery required to bring a grand jury into being did not exist.
In subsequent correspondence, Judge Christian suggested that the Justice Department persuade the Virgin Islands Legislature to enact a statute authorizing an investigatory grand jury. If that effort failed, the judge suggested that the Justice Department might utilize the special subpoena powers conferred on the U.S. Attorney for the Virgin Islands by the Virgin Islands Legislature.
It was at that point that the Justice Department abandoned all reliance on § 3331.1 Instead, the Justice Department then asked that an investigatory grand jury be convened pursuant to Rule 6(a) of the Federal Rules of Criminal Procedure. When Chief Judge Christian refused to convene the grand jury sought by the Justice Department, the present petition for a writ of mandamus, pursuant to 28 U.S.C. § 1651, was filed.
The writ sought to have this court direct the District Court of the Virgin Islands to convene a grand jury for the limited purpose of investigation pursuant to Fed.R. Crim.P. 6(a). In its petition, the United States, after maintaining that mandamus was a proper remedy for the district court’s refusal to summon an investigatory grand jury, asserted that enforcement of federal laws in the Virgin Islands would be “crippled” if investigatory grand juries could not *905be convened there. The United States then claimed that Rule 54(a) of the Federal Rules of Criminal Procedure and 48 U.S.C. § 1615 (1976)2 (Section 25 of the Virgin Islands Revised Organic Act) only preclude the initiation of prosecution by a grand jury. Rule 54(a) reads:
(a) Courts. These rules apply to all criminal proceedings in the United States District Courts; in the District Court of Guam; in the District Court of the Virgin Islands; and (except as otherwise provided in the Canal Zone Code) in the United States District Court for the District of the Canal Zone; in the United States Courts of Appeals’ and in the Supreme Court of the United States; except that all offenses shall continue to be prosecuted in the District Court of Guam and in the District Court of the Virgin Islands by information as heretofore except such as may be required by local law to be prosecuted by indictment by grand jury. (emphasis added)
Since the Federal Rules of Criminal Procedure apply in the District Court of the Virgin Islands, the United States contended “Rule 6(a) powers” extend to the Virgin Islands to the extent that these powers provide for an investigatory grand jury which has no power of indictment.
According to the petition of the United States:
It is possible “to give effect to both” provisions by reading them as allowing the calling of investigative grand juries in the Virgin Islands under Rule 6(a), but requiring, pursuant to Rule 54(a) and 48 U.S.C. § 1615, prosecution by'information. While grand juries traditionally perform both investigative and accusatory functions, Congress on occasion contemplates that grand juries might investigate crimes without issuing indictments. See, e. g., Rule 7(a) of the Federal Rules of Criminal Procedure; 18 U.S.C. § 3333.4 Grand jury investigative authority is deeply ingrained in American jurisprudence, see United States v. Calandra, 414 U.S. 338, 343-44, 94 S.Ct. 613, 617-618, 38 L.Ed.2d 561 (1974); Branzburg v. Hayes, 408 U.S. 665, 688, 92 . S.Ct. 2646, 2660, 33 L.Ed.2d 626 (1972); Blair v. United States, 250 U.S. 273, 280, 282, 39 S.Ct. 468, 470, 63 L.Ed. 979 (1919); Hale v. Henkel, 201 U.S. 43, 64-65, 26 S.Ct. 370, 374-375, 50 L.Ed. 652 (1906), and it is implausible that Congress intended indirectly to abrogate this power in the Virgin Islands by insisting on prosecution by information.
Petition for the United States at 4-5.
In its final argument, the United States relied on the legislative history of the 1954 amendment to Section 25 of the Revised Organic Act of the Virgin Islands, which provides for continued prosecution by information. The main purpose of this amendment, the United States argued, was to prevent the release of prisoners who, up until that time, had not been indicted by (or waived indictment by) a grand jury. The government’s version of the legislative history revealed no hostility to the grand jury as an institution, and more particularly, to an investigatory grand jury.
The answering and supplementary briefs of the United States essentially embellished its original reasoning. The government noted that the Jury Selection and Service Act, 28 U.S.C. §§ 1861, et seq. (1976), which provides the methods for selecting both grand and petit juries, applies to the District Court of the Virgin Islands, 28 U.S.C. § 1869(f) (1976). The United States argued that these provisions contemplate the use of a grand jury in the Virgin Islands. In its supplementary brief, the government, ex*906plained why available, alternative means of investigation — means which the government apparently never attempted to pursue — were and are less satisfactory than a grand jury investigation.
In essence, therefore, the government’s bottom line is that Rule 6(a) and Rule 7 of the Federal Rules of Criminal Procedure provide the only source of authority available for the convening of an investigatory grand jury.
II.
■ I observe.that in defining the role of an indicting grand jury convened under Rule 6, the courts have not limited themselves to the legislative history of the Fed.R.Crim.P., but have also looked to common law powers and the fifth amendment. United States v. Calandra, 414 U.S. 338, 342-44, 94 S.Ct. 613, 616-18, 38 L.Ed.2d 561 (1974). Judge Adams has explored these sources of authority in section III of the majority opinion. I make no comment with respect to that discussion because of the context in which the issue of grand jury authority has been presented to us. The government, as Judge Adams and I both note, has restricted its entire argument to Rules 6 and 7. This being so, in our disposition of the government’s petition, we need go no further than an analysis limited to just those Rules.
A.
As Judge Adams and I have noted, the full weight of the government’s argument rests on Rules 6 and 7 as the source of authority for convening an investigatory grand jury in the Virgin Islands. Even were we to limit our analysis solely to the rules relied upon by the government, it follows inexorably that an investigatory grand jury is not authorized under Rules 6, 7. Rule 6 does not refer to an “investigatory” grand jury. It does not provide for a grand jury to write reports or for a grand jury to return presentments.
Rule 6(a) reads:
(a) Summoning Grand Juries. The court shall order one or more grand juries to be summoned at such times as the public interest requires. The grand jury shall consist of not less than 16 nor more than 23 members. The court shall direct that a sufficient number of legally qualified persons be summoned to meet this requirement.
Certainly, the language of this rule does not recognize the existence of any sort of investigatory grand jury. The phrase, “as the public interest requires,” which I have underlined in the text above can only have reference to, and thus modify, the times when a grand jury may be summoned — not the type of grand jury that can be summoned. Notes of Advisory Committee, 18 U.S.C.A. Fed.R.Crim.P. 6 at 268.
The government has pointed to no legislative history or case law that indicates that an investigatory grand jury can be convened under Rule 6(a). None of the authorities referred to by the United States supports the proposition that Rule 6(a) authorizes an investigatory grand jury which has no power of indictment. None lend any basis to its theory that “Congress has granted grand juries in the Virgin Islands a limited role: to investigate crimes but to leave prosecution in the hands of the prosecutors.” (United States Answering Brief at 2).
Nor can the government place any reliance on Rule 7(a) of the Federal Rules of Criminal Procedure,3 which it cites in support of its theory that an investigatory grand jury may be convened pursuant to Rule 6. Rule 7(a) is concerned only with indictments and informations. Thus, as might be expected, the Supreme Court *907cases cited by the United States only make reference to an indicting grand jury.4
Indeed, additional examination into Rules 6 and 7 completely refutes the government’s arguments that the Rules provide any authority for convening an investigatory grand jury. Rule 6 appears under a heading which reads “HI. Indictment and Information.” This heading alone indicates that only a grand jury with indicting powers could be summoned under Rule 6. Federal Rule of Criminal Procedure 7 delineates the use of an indictment for a grand jury convened under Rule 6. Rule 7 makes no provision for a grand jury that only has investigatory powers, nor does it provide for a grand jury to write reports or issue presentments.
B.
The Advisory Committee Note to Fed.R. Crim.P. 7 states that this Rule gives effect to the fifth amendment grand jury clause. 18 U.S.C.A. Fed.R.Crim.P. at 388, In addition, courts have looked to the fifth amendment as well as to English common law in delimiting the role of an indicting. grand jury convened under Rule 6. See, e. g., United States v. Calandra, 414 U.S. 338, 342-43, 94 S.Ct. 613, 616-18, 38 L.Ed.2d 561 (1979). If, as these authorities suggest, the Federal Rules of Criminal Procedure implement powers of the grand jury implied from the fifth amendment, then it cannot be that these same Rules constitute the sole source of a court’s authority to convene a grand jury. The Rules only provide the procedures that govern grand juries, which have been convened by virtue of a pre-existing authority.
It cannot be disputed that the fifth amendment does not mandate the use of a purely investigatory grand jury. Nor can it be said that an investigatory grand jury arises from a necessary implication of the fifth amendment. The investigatory grand jury which the government urges may be convened under Rule 6, actually appears to be at odds with the requirements of the fifth amendment and the provisions implementing it. A federal grand jury acts as both a sword and a shield. See United States v. Cox, 342 F.2d 167, 186 (5th Cir.) (en banc) (Wisdom, J., concurring specially), cert. denied, 381 U.S. 935, 85 S.Ct. 1767, 14 L.Ed.2d 700 (1965). It serves as a means to bring to trial those suspected of crimes and serves as a protection against malicious and harassing prosecution. See, e. g., United States v. Calandra, 414 U.S. 338, 343, 94 S.Ct. 613, 618, 38 L.Ed.2d 561 (1974). This latter protective function reflects the essential purpose of the fifth amendment in safeguarding the rights of an individual. The fifth amendment was designed for the benefit of the accused: to afford a safeguard against oppressive action of a prosecutor or a court. United States v. Cox, 342 F.2d 167, 170 (5th Cir.) (en banc) (opinion of Jones, J.), cert. denied, 381 U.S. 935, 85 S.Ct. 1767, 14 L.Ed.2d 700 (1965).
An investigatory grand jury which has no power of indictment serves little, if any, protective purpose. It cannot refuse to indict an individual. To the extent that the role of an investigatory grand jury is defined by the government, it apparently is designed only to ferret out crime. Thus, to authorize the summoning of an investigatory grand jury under the Federal Rules of Criminal Procedure, which were designed to implement the fifth amendment, would be to ignore the essential protective function of that constitutional provision. See United States v. Briggs, 514 F.2d 794, 803 (5th Cir. 1975).
Moreover, as we have observed, since these Rules implement the fifth amendment, it follows that in those instances where these fifth amendment protections are inapplicable, the federal rules providing for grand juries are also inapplicable. This Court has consistently held that the fifth amendment’s grand jury protection does not extend to prosecutions initiated in the *908Virgin Islands. See, e. g., Government of Virgin Islands v. Dowling, 633 F.2d 660, 667 (3d Cir.) (Maris J.), cert. denied, 449 U.S. 960, 101 S.Ct. 374, 66 L.Ed.2d 228 (1980); Rivera v. Government of the Virgin Islands, 375 F.2d 988 (3d Cir. 1967). It is thus not surprising that the Revision Notes to 5 V.I. § 3581 (1967) state that Rule 6 and Rule 7(a), (b) of the Federal Rules of Criminal Procedure do not apply in the Virgin Islands.
Thus, there can be no basis for asserting that Rules 6 and 7 may serve as authority for the convening of an investigatory grand jury in the Virgin Islands.
C.
Indeed, I search in vain for the institution called the investigatory grand jury, an institution which the government now urges us to create out of whole cloth. Of course, grand juries have investigatory powers. These powers though are a necessary adjunct to their power to indict. The function of a grand jury is only to decide whether to indict or not to indict. 1 C. Wright, Federal Practice and Procedure, § 110 at 197 (1969). Yet, without any authority, the government would have us sever the subsidiary investigatory function of the grand jury from its other functions and create a new creature.
I agree with the majority opinion that only the Congress or the Virgin Islands Legislature may establish an investigatory grand jury in the Virgin Islands. I emphasize that it is for the legislative, not the judicial, branch to decide whether to create such an institution. If we were to adopt the reasoning of the government we would overturn the common understanding in the Virgin Islands concerning the nature of its own criminal investigation system. No grand jury has ever been convened in the Virgin Islands. We were told at oral argument that not only is the apparatus lacking to convene a grand jury, but that inordinate practical problems would be encountered if a grand jury were to be ordered. I do not think we should ignore the Virgin Islands practice and understanding without clear authority from Congress.
III.
Even had this panel reached a contrary conclusion as to the scope of Rules 6 and 7, and had consequently held that these Rules did indeed constitute authority for the summoning of an investigatory grand jury in the Virgin Islands, I nevertheless would have refused to issue the writ of mandamus sought by the government.
It must be remembered that the writ of mandamus is a drastic remedy that will “issue only in extraordinary circumstances ... ”, Kerr v. United States District Court, 426 U.S. 394, 402-03, 96 S.Ct. 2119, 2123-2124, 48 L.Ed.2d 725 (1976). The party seeking mandamus has “the burden of showing that its right to issuance of the writ is ‘clear and indisputable.’ ” Will v. United States, 389 U.S. 90, 96, 88 S.Ct. 269, 274, 19 L.Ed.2d 305 (1967) quoting Bankers Life & Cas. Co. v. Holland, 346 U.S. 379, 384, 74 S.Ct. 145, 148, 98 L.Ed. 106 (1953). See also Allied Chemical Corp. v. Daiflon, Inc., 449 U.S. 33, 101 S.Ct. 188, 66 L.Ed.2d 193 (1980); Kerr, supra, 426 U.S., at 403, 96 S.Ct. at 2124; United States v. Duell, 172 U.S. 576, 582,19 S.Ct. 286, 287, 43 L.Ed. 559 (1899); United States v. Cuthbertson, 651 F.2d 189 at 193 (3d Cir. 1981).
The burden is on the petitioner, here the United States, to show that it has a “clear and indisputable” right to the writ. In addition, our issuance of the writ is largely discretionary. Kerr, supra, 426 U.S., at 403, 96 S.Ct. at 2124. Thus, in my opinion, the party seeking a writ of mandamus must first provide an explicit and detailed explanation of the relief which it seeks. Mandamus relief should be unavailable if the party seeking it furnishes only a vague description of the duty which the district court should be compelled to exercise. Yet here the United States has not only failed to provide us with a clear explanation of the relief which it desires, but it has also failed to outline the precise powers and functions of the investigatory grand jury which it *909seeks, and the necessary procedural safeguards under which it should operate.5
Although the United States does refer to judicial and statutory authority describing various possible functions of an investigatory grand jury, the government does not employ these authorities to delineate the functions of, or provide for, the powers of the investigatory grand jury that it has requested. Whatever the government may envisage the powers and functions of an investigatory grand jury to be, all I can gather from the government’s brief and petition is that there is one function and power such a grand jury would not have— the power to indict. As a consequence, we have been provided with no description of the nature, functions or powers of the investigatory grand jury which the government desires the district court to summon.
I do not see how we could order the district court to convene such a grand jury of such an unknown nature and such unknown powers. Of course, this court can define what we believe to be the appropriate powers of a federal investigatory grand jury, but I do not believe that to be our role. Hence, even if I were to accept the United States’s assertion that an investigatory grand jury could be empanelled under Rule 6(a), I would still refuse to grant the government’s petition for a writ of mandamus because no functions, powers, or safeguards concerning such a grand jury have been identified, let alone authorized. In failing to do so, the government, in my opinion, has fallen far short of demonstrating a “clear and indisputable” right to mandamus relief.
APPENDIX A
18 U.S.C. § 3331. Summoning and term
(a) In addition to such other grand juries as shall be called from time to time, each district court which is located in a judicial district containing more than four million inhabitants or in which the Attorney General, the Deputy Attorney General, or any designated, Assistant Attorney General, certifies in writing to the chief judge of the district that in his judgment a special grand jury is necessary because of criminal activity in the district shall order a special grand jury to be summoned at least once in each period of eighteen months unless another special grand jury is then serving. The grand jury shall serve for a term of eighteen months unless an order for its discharge is entered earlier by the court upon a determination of the grand jury by majority vote that its business has been completed. If, at the end of such term, or any extension thereof, the district court determines the business of the grand jury has not been completed, the court may enter an order extending such term for an additional period of six months. No special grand jury term so extended shall exceed thirty-six months, except as provided in subsection (e) of Section 3333 of this chapter.
These grand juries have the duty “to inquire into offenses against the criminal laws of the United States,” 18 U.S.C. § 3332 (1976), and are authorized to submit a report:
(1) concerning noncriminal misconduct, malfeasance, or misfeasance in office in*910volving organized criminal activity by an appointed public officer or employee as thé basis for a recommendation of removal or disciplinary action; or
(2) regarding organized crime conditions in that district. <
18 U.S.C. § 3333(a) (1976).
Before such a report is permitted to be published, a number of procedural safeguards must be met.
To the extent they are not inconsistent with §§ 3331-33, the provisions of the United States Code and Federal Rules of Criminal Procedure applicable to “regular grand juries” are also applicable to special grand juries. 18 U.S.C. § 3334 (1976).
. United States v. Calandra, 414 U.S. 338, 343-344, 94 S.Ct. 613, 617-618, 38 L.Ed.2d 561 (1974); Branzburg v. Hayes, 408 U.S. 665, 688, 92 S.Ct. 2646, 2660, 33 L.Ed.2d 626 (1972); Blair v. United States, 250 U.S. 273, 280, 282, 39 S.Ct. 468, 470, 63 L.Ed. 979 (1919); Hale v. Henkel, 201 U.S. 43, 64-65, 26 S.Ct. 370, 374-375, 50 L.Ed. 652 (1906).
. It is my belief that the government abandoned its § 3331 argument not only because the “district court” to which the statute refers necessarily excludes the District Court of the Virgin Islands, but also because an examination of §§ 3331-34 reveals that the mere existence of these statutes lends support not to the government’s thesis but to the respondent’s. For ease in reference I attach the relevant portions of these statutes as Appendix A to this opinion.
It should be observed that the special grand juries permitted under §§ 3331-34 can only be convened for the purpose of investigating criminal violations, and that such grand juries have the power to indict. The Senate report accompanying the Act states:
Section 3332(b) defines the scope of the power of the special grand jury to investigate “offenses against the criminal laws of the United States. ...” It reflects present law. See Hale v. Henkel, 201 U.S. 43, 26 S.Ct. 370, 50 L.Ed. 652 (1906); Blair v. United States, 250 U.S. 273, 39 S.Ct. 468, 63 L.Ed. 979 (1919). Collateral inquiry which results in a report is contemplated tinder section 3332. However, this section makes it clear that investigations are to be conducted only into criminal offenses against the United States, and not for the sole purpose of report writing.
Consequently, even under §§ 3331-34, a grand jury cannot be convened solely for the purpose of investigating. As the Senate Report indicates, the main function of a special grand jury is the same as a Rule 6 grand jury: to investigate crime and to determine whether indictments should be returned. Its reporting power, limited to noncriminal misconduct and organized crime conditions, is “collateral.”
The special grand jury in the Virgin Islands sought by the government could only be authorized for “the sole purpose of report writing,” since section 25 of the Revised Organic Act of the Virgin Islands, 48 U.S.C. § 1615, provides for prosecution by information rather than by indictment, unless otherwise required by local law. Thus, the summoning of this purely investigatory grand jury would clearly contravene the intent of Congress in enacting 18 U.S.C. §§ 3331-34.
Therefore, I am convinced, as the government must have been, that §§ 3331-34 provide no authority for summoning an investigatory grand jury in the Virgin Islands.
. Section 1615 provides that in the District Court of the Virgin Islands:
All offenses shall continue to be prosecuted in the District Court by information as heretofore except such as may be required by local law to be prosecuted by indictment by grand jury.
Investigatory grand juries are also permitted in 18 states in which the prosecutor may proceed by information. See Branzburg v. Hayes, 408 U.S. 665, 688 n. 25, 92 S.Ct. 2646, 2660 n. 25, 33 L.Ed.2d 626 (1972).
. Rule 7(a) reads:
■(a) Use of Indictment of Information. An offense which may be punished by death shall be prosecuted by indictment. An offense which may be punished by imprisonment for a- term exceeding one year or at hard labor shall be prosecuted by indictment or, if indictment is waived, it may be prosecuted by information. Any other offense may be prosecuted by indictment or by information. Any information may be filed without leave of court.
. 1 observe that when Congress authorized “special grand juries” under 18 U.S.C. § 3331, it took pains to include in the statutory scheme, the powers, and functions of such grand juries. Significantly, Congress also included a number of procedural safeguards. For example, 18 U.S.C. § 3333 prohibits the district court from making a report public unless the report is supported by a preponderance of the evidence, persons named in the report have been given an opportunity to testify and call witnesses, and public officials named are given an opportunity to file an answer which becomes an appendix to the report.
Similarly, when the Commonwealth of Pennsylvania enacted legislation providing for “investigating grand juries,” it set out in great detail the powers, composition, and functions of such institutions and provided as well for safeguards in connection with their operation. See Pa.Cons.Stat.Ann. §§ 4541-53.
It cannot be disputed that neither Rule 6 nor Rule 7, nor for that matter any other statute or Rule, provide the federal system with the structure for an investigatory grand jury. Nor do they provide for the powers or functions that such a grand jury would possess.