on the ground that defendant waived his Speech or Debate privilege by voluntarily testifying before the grand jury about his legislative acts.
A.
The All Writs Act empowers the Courts of Appeals to “issue all writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principles of law.” 28 U.S.C. § 1651 (1970).
The Act has been read to grant us jurisdiction to issue a writ of mandamus where the underlying proceeding is one either actually or potentially within our appellate jurisdiction. Since the prosecution of this defendant for the violation of federal bribery laws is a ease potentially within our appellate jurisdiction, we have the jurisdiction to grant the writ defendant seeks. “Hence the question presented on this record is not whether [we have] power to grant the writ but whether in the light of all the circumstances the case [is] an appropriate one for the exercise of that power.” Roche v. Evaporated Milk Association, 319 U.S. 21, 25-26, 63 S.Ct. 938, 941, 87 L.Ed. 1185 (1943).
The Supreme Court recently has emphasized that, in determining when it is “appropriate” to issue the writ we must keep in mind that “[t]he remedy of mandamus is a drastic one, to be invoked only in extraordinary situations.” Kerr v. United States District Court, 426 U.S. 394, 402, 96 S.Ct. 2119, 2123, 48 L.Ed.2d 725 (1976).
Generally, federal courts have used the writ “to confine an inferior court to a lawful exercise of its prescribed jurisdiction or to compel it to exercise its authority when it is its duty to do so.” Roche v. Evaporated Milk Association, 319 U.S. 21, 26, 63 S.Ct. 938, 941, 87 L.Ed. 1185 (1943), quoted in Kerr v. United States District Court, 426 U.S. 394, 402, 96 S.Ct. 2119, 2124, 48 L.Ed.2d 725 (1976). And while the Supreme Court in Kerr noted that it had “not limited the use of mandamus by an unduly narrow and technical understanding of what constitutes a matter of ‘jurisdiction,’ ” the Court stressed that the writ should issue only in extraordinary situations: “the fact still remains that ‘only exceptional circumstances amounting to a judicial “usurpation of power” will justify the invocation of this extraordinary remedy.’ ” Kerr v. United States District Court, 426 U.S. 394, 402, 96 S.Ct. 2119, 2124, 48 L.Ed.2d 725 (1976), quoting Will v. United States, 389 U.S. 90, 95, 88 S.Ct. 269, 19 L.Ed.2d 305 (1967).
In order to further the congressional determination that appellate review should come only after final judgment except in the most exceptional circumstances, the courts also have required that even where circumstances amount to a “judicial usurpation of power,” the petitioner must satisfy certain other conditions for issuance of the writ. Thus, the party seeking the writ must have no other adequate means to attain the relief he seeks. And petitioner also must show that his right to issuance of the writ is clear and indisputable. Id. 426 U.S. at 403, 96 S.Ct. at 2124.
Finally, “it is important to remember that issuance of the writ is in large part a matter of discretion with the court to which the petition is addressed.” Id.
In light of these principles we examine the grounds asserted by defendant in support of his petition in order to determine if issuance of the writ is appropriate in this case.
B.
Defendant first argues that the district court is without jurisdiction to try the defendant because the indictment charges him with legislative acts. Apparently, the defendant believes that the specific references to the introduction of private bills in the first four counts establish that this indictment is actually one charging the defendant with the performance of legislative acts and so violates the Speech or Debate privilege.
The defendant distinguishes this indictment from those at issue in United States v. Brewster, 408 U.S. 501, 92 S.Ct. 2531, 33 L.Ed.2d 507 (1972), and United States v. Johnson, 383 U.S. 169, 86 S.Ct. 749, 15