opinion: SPOTTSWOOD W. ROBINSON, III, Circuit Judge:
  This case is before the court on a petition for a writ of mandamus directing the Honorable Barrington D. Parker, a United States District Judge for the District of Columbia, to order physical and mental examination of Catherine W. Kunz, the .plaintiff named in an action brought against petitioner and another in the District Court. Judge Parker denied petitioner’s motion for the examinations, and the validity of that ruling is a subject of lively argumentation here. We find it unnecessary to enter the debate on that score for we accept the further contention that, in the circumstances presented here, the ruling is not reviewable by way of mandamus. We accordingly deny the writ.
  I
  Petitioner is an attorney practicing in the District of Columbia. He was joined as a party defendant in a suit filed in the name of Mrs. Kunz, a former client. The complaint therein alleges that petitioner caused an unauthorized disposition to be made of securities owned by Mrs. Kunz, and it seeks a return of the securities or damages.
  Petitioner defends on the ground that Mrs. Kunz gave him ownership of the securities in partial payment of a fee for services rendered in her behalf. Petitioner also says that Mrs. Kunz was satisfied with the services, and that she is not the moving spirit behind the litigation. In fact, asserts petitioner, subsequent to completion of the services, her health deteriorated to the point that she lacked capacity to bring the action.
  That Mrs. Künz has been victimized by sudden and serious illness is conceded. The discord, rather, is over the condition in which the illness has left her and its impact upon the proceeding. The dispute ripened for judicial consideration when petitioner gave notice that he would take Mrs. Kunz’ deposition. Her counsel then moved for an order barring that activity on the ground that she was “unable to withstand the rigors of a deposition and is further in such a state of mental and physical debility that she is unable at the present time to answer questions concerning this matter.” The .motion was supported by the affidavit of Mrs. Kunz’ attending physician stating that she “is not physically or mentally able to undergo an oral deposition and may not be fit to do so for some time to come.” The affidavit added that Mrs. Kunz “is approximately 76 years old and the rigors of an oral deposition at this time would endanger her health and life.” Judge Parker granted the motion, and the deposition was thus precluded.
  Promptly thereafter, petitioner filed his own motion for an order directing physical and mental examinations of Mrs. Kunz. The motion warned that in the event that the examinations disclosed mental disability, petitioner would move to dismiss the lawsuit as spurious. The motion was accompanied by petitioner’s affidavit stating his belief that the suit had been filed without Mrs. Kunz’ authority. The motion was opposed on grounds that Mrs. Kunz’ physical-mental condition was not in controversy, and that good cause for the examinations had not been shown. The opposition also claimed that Mrs. Kunz was competent when she obtained counsel and authorized him to sue. Judge Parker denied the motion and petitioner,
  now invoking the All Writs Act, seeks relief at the hand of this court.
  II
  As the Supreme Court admonishes, “[t]he peremptory writ of mandamus has traditionally been used in the federal courts only ‘to confine an inferi- or 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.’ ” That is not to say, however, that every jurisdictional excess or omission will support a call for mandamus against a federal judge. For “[w]hile the courts have never confined themselves to an arbitrary and technical definition of ‘jurisdiction,’ it is clear that only exceptional circumstances amounting to a judicial ‘usurpation of power’ will justify the invocation of this extraordinary remedy.” And while in an unusual case mandamus may lie to enforce the performance of a judicial responsibility, it is well settled that it cannot be used as a substitute for appeal. The proponent of mandamus has “the burden of showing that [his] right to issuance of the writ is ‘clear and indisputable.’ ”
  Plainly, in the case at bar, the District Judge did not exceed his jurisdiction — in any real sense of the word. Capacity of an individual, not acting in a representative character, to sue or be sued in the federal courts is ordinarily to be determined by the law of his domicile. The record before us does not permit a satisfactory conclusion as to where Mrs. Kunz is domiciled or, of course, as to just what her mentality may be, but these matters are of little moment to jurisdiction. If by the law of her domicile she can sue irrespective of actual mental incompetence, she may do so in any federal court. But even if the domiciliary law undertook to withdraw that attribute because of mental disability, litigation of her rights in the District Court is still to be governed by Federal Civil Rule 17(c). That rule provides that “[t]he court shall appoint a guardian ad litem for an . incompetent person not otherwise represented in an action or shall make such other order as it deems proper for the protection of the . . . incompetent person.” So, state law may confer but not deny capacity to sue or defend federally, and the only effect of a party’s incompetence upon maintenance of the action is the possible need for appointment of a guardian ad litem or entry of a protective order. In no event is federal jurisdiction to entertain the cause diminished.
  Ill
  The only other claim open to petitioner was that the circumstances put Judge Parker under a duty to issue the examinatorial order sought. The evidence of the poor state of Mrs. Kunz’ health could, on petitioner’s challenge, have presented the occasion for an inquiry into her capacity to understand the meaning and effect of the litigation being prosecuted in her name. Beyond that, despite the earlier ruling adverse to petitioner’s effort to depose Mrs. Kunz, he was entitled to a fair opportunity to contest the affidavit averring that an attempt to do so would be unwise. And surely a court-ordered physical-mental examination of Mrs. Kunz, conducted under appropriate safeguards, might have developed important information to serve both of those purposes, and thus to materially advance the progress of the suit toward a final judgment on the merits.
  In the present procedural posture of the case, however, these considerations are beside the point. They do not survive the threshold question whether the contested ruling can now be reviewed in a mandamus proceeding or whether review must await the District Court’s final disposition. As the Supreme Court has observed, “[a] 11 our jurisprudence is strongly colored by the notion that appellate review should be postponed, except in certain narrowly defined circumstances, until after final judgment has been rendered by the trial court.” Mandamus “does not ‘run the gauntlet of reversible errors’ ” ; it “may not be used to thwart the congressional policy against piecemeal appeals.” Only where an appeal can promise no more than “a clearly inadequate remedy” may the remedy of mandamus be resorted to.
  The order denying the examinations, and foreclosing the discovery which petitioner sought thereby, was interlocutory and nonappealable. The cases denying review of discovery orders by mandamus are legion. Petitioner has not shown, nor are we able to perceive, any peculiar circumstance which would set this case apart as truly unusual. On the contrary, the most that can be urged is that Judge Parker erred in applying the standards for physical-mental examinations to the situation displayed, and mandamus simply does not reach to such an error.
  The question is not whether petitioner can obtain review of the ruling on the examination issue, but whether he can do so now. Should petitioner’s defensive efforts in the District Court prove to be ultimately unsuccessful, he can litigate that ruling, if unchanged, on an appeal from the final judgment. No rights will be jeopardized, no irreparable injury will be suffered, nor will any position be irreversibly compromised. To be sure, petitioner may incur added expense, encounter added delay and perhaps even be subjected to an unnecessary trial, but “that inconvenience is one which we must take it Congress contemplated in providing that only final judgments should be reviewable.”
  In sum, “[t]he peremptory common-law writs are among the most potent weapons in the judicial arsenal,” and “[a]s extraordinary remedies, they are reserved for. really extraordinary causes.” The case before us is not of that character. The writ of mandamus which petitioner seeks must accordingly be denied.
  Writ denied.
  . But see text infra at notes 13-19.
  . “When the mental or physical condition (including the blood group) of a party, or of a person in the custody or under the legal control of a party, is in controversy, the court in which the action is pending may order the party to submit to a physical or mental examination by a physician or to produce for examination the person in his custody or legal control. The order may be made only on motion for good cause shown and upon notice to the person to be examined and to all parties and shall specify the time, place, manner, conditions, and scope of the examination and the person or persons by whom it is to be made.” Fed.R.Civ.P. 35(a).
  . See note 2, supra. See also Schlagenhauf v. Holder, 379 U.S. 104, 116-122, 85 S.Ct. 234, 13 L.Ed.2d 152 (1964).
  . Counsel filed in the District Court an affidavit stating that Mrs. Kunz, while lucid, had personally appeared in his office and affirmed the allegations on which the suit is founded. Counsel’s theory is that notwithstanding her subsequent illness, he had full authority to proceed in her behalf. But see note 20, infra.
  . “The Supreme Court and all courts established by Act of Congress may 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(a) (1970).
  . Petitioner joined Mrs. Kunz and his code-fendant with Judge Parker as corespondents to the petition for mandamus. He now asks for an order requiring counsel for Mrs. Kunz to show his authority to represent her here. The cornerstone of this request is the premise which is basic to petitioner’s bid for mandamus — that Mrs. Kunz may be mentally incompetent — and from this petitioner argues that if in fact she is incompetent, her counsel’s authority has terminated. See note 20, infra. We have undoubted power to require counsel before us to demonstrate their authority, e. g., Pueblo of Santa Rosa v. Fall, 273 U.S. 315, 319, 47 S.Ct. 361, 71 L.Ed. 658 (1927), but the circumstances militate against an exercise of discretion to require it here. Mrs. Kunz’ physical-mental condition remains a burning issue in the District Court; indeed, it may be the pivot upon which much of the case on the merits will turn. That court is the forum in which a resolution of the issue should be undertaken in the first instance. Moreover, this court is not equipped to embark upon the kind of evidentiary exploration which a controversy of this sort obviously demands. Counsel should be permitted to continue his representation, both here and in the District Court, until the question can suitably be determined there.
  . Will v. United States, 389 U.S. 90, 95, 88 S.Ct. 269, 19 L.Ed.2d 305 (1967), quoting Roche v. Evaporated Milk Ass’n, 319 U.S. 21, 26, 63 S.Ct. 938, 87 L.Ed. 1185 (1943). See, to the same effect, Schlagenhauf v. Holder, supra note 3, 379 U.S. at 109-110, 85 S.Ct. 234; Bankers Life & Cas. Co. v. Holland, 346 U.S. 379, 382, 74 S.Ct. 145, 98 L.Ed. 106 (1953).
  . Will v. United States, supra note 7, 389 U.S. at 95, 88 S.Ct. at 273, quoting De Beers Consol. Mines v. United States, 325 U.S. 212, 217, 65 S.Ct. 1130, 89 L.Ed. 1566 (1945). See, to the same effect, Ex parte Fahey, 332 U.S. 258, 260, 67 S.Ct. 1558, 91 L.Ed. 2041 (1947).
  . E. g., McClellan v. Carland, 217 U.S. 268, 279-282, 30 S.Ct. 501, 54 L.Ed. 762 (1910) (refusal to proceed with case) ; In re Winn, 213 U.S. 458, 465-468, 29 S.Ct. 515, 53 L. Ed. 873 (1909) (refusal to remand case) ; In re Grossmayer, 177 U.S. 48, 49-50, 20 S.Ct. 535, 44 L.Ed. 665 (1900) (refusal to take jurisdiction) ; Ex parte Schollenberger, 96 U.S. (6 Otto) 369, 374-378, 24 L.Ed. 853 (1878) (refusal to take jurisdiction) ; Stafford v. Union Bank, 58 U.S. (17 How.) 275, 283-284, 15 L.Ed. 101 (1854) (refusal to issue execution) ; Life & Fire Ins. Co. v. Wilson, 33 U.S. (8 Pet.) 291, 301-304, 8 L. Ed. 949 (1834) (refusal to sign judgment) ; Yablonski v. UMW, 147 U.S.App.D.C. 193, 195, 454 F.2d 1036, 1038 (1971), cert, denied, 406 U.S. 906, 92 S.Ct. 1609, 31 L.Ed. 2d 816 (1972) (refusal to follow mandate).
  . See discussion in text infra at notes 23-26.
  . Bankers Life & Cas. Co. v. Holland, supra note 7, 346 U.S. at 384, 74 S.Ct. at 148, quoting United States v. Duell, 172 U.S. 576, 582, 19 S.Ct. 286, 43 L.Ed. 559 (1899). Accord, Will v. United States, supra note 7, 389 U.S. at 96, 88 S.Ct. 269.
  . As the Court stated in Will v. United States, supra note 7, 389 U.S. at 98 n. 6, 88 S.Ct. at 275, it will not do “to argue that a judge has no ‘power’ to enter an erroneous order. Acceptance of this semantic fallacy would undermine the settled limitations upon the power of an appellate court to review interlocutory orders. Neither ‘jurisdiction’ nor ‘power’ can be said to ‘run the gauntlet of reversible errors.’ Bankers Life & Cas. Co. v. Holland, 346 U.S. 379, 382, 74 S.Ct. 145, 147 [98 L.Ed. 106] (1953). Courts faced with petitions for the peremptory writs must be careful lest they suffer themselves to be misled by labels such as ‘abuse of discretion’ and ‘want of power’ into interlocutory review of nonappealable orders on the mere ground that they may be erroneous.”
  . Fed.R.Civ.P. 17(b). See Slade v. Louisiana Power & Light Co., 418 F.2d 125, 126 • (5th Cir. 1969), cert, denied, 397 U.S. 1007, 90 S.Ct. 1233, 25 L.Ed.2d 419 (1970) ; Brimhall v. Simmons, 338 F.2d 702, 706 (6th Cir. 1964) ; Redditt v. Hale, 184 F.2d 443, 447 (8th Cir. 1950) ; 6 C. Wright & A. Miller, Federal Practice § 1571 (1971). But see Fallat v. Gouran, 220 F.2d 325, 328-329 (3d Cir. 1955).
  . Seemingly, the point has not been directly litigated in the District Court.
  . Bengtson v. Travelers Indem. Co., 132 , F.Supp. 512, 517 (W.D.La.1955), aff’d, 231 F.2d 263 (5th Cir. 1956) ; First Nat’l City Bank v. Gonzalez & Co. Sucr. Corp., 308 F.Supp. 596, 600 (D.Puerto Rico 1970) ; 6 C. Wright & A. Miller, Federal Practice § 1571 (1971). See also Hanna v. Plumer, 380 U.S. 460, 469—474, 85 S.Ct. 1136, 14 L. Ed.2d 8 (1965) ; Constantine v. Southwestern Louisiana Institute, 120 F.Supp. 417, 418—419 (W.D.La.1954).
  . “Whenever an infant or incompetent person has a representative, such as a general guardian, committee, conservator, or other like fiduciary, the representative may sue or defend on behalf of the infant or incompetent person. If an infant or incompetent person does not have a duly appointed representative he may sue by his next friend or guardian ad litem. The court shall appoint a guardian ad litem for an infant or incompetent person not otherwise represented in an action or shall make such other order as it deems proper for the protection of the infant or incompetent person.” Fed.R.Civ. P. 17(e).
  . See authorities cited supra notes 13, 15.
  . See Roberts v. Ohio Cas. Ins. Co., 256 F.2d 35, 38-39, 68 A.L.R.2d 747 (5th Cir. 1958) ; United States v. Noble, 269 F.Supp. 814, 815 (E.D.N.Y.1967).
  . See New Mexico Veterans’ Serv. Comm’n v. United Van Lines, 325 F.2d 548, 550 (10th Cir. 1963). See also Till v. Hartford Accident & Indem. Co., 124 F.2d 405, 408-409 (10th Cir. 1941) ; Rutland v. Sikes, 203 F.Supp. 276, 277 (E.D.S.C.), aff’d, 311 F.2d 538 (4th Cir. 1962), cert, denied, 374 U.S. 830, 83 S.Ct. 1871, 10 L.Ed.2d 1053 (1963).
  . As we have said, Fed.R.Civ.P. 17 (c) directs district courts to either appoint guardians ad litem or fashion protective orders for incompetent persons not otherwise represented. See text supra at notes 15-19. Moreover, insanity or other severe mental difficulty of a client may operate to suspend or terminate a preexisting attorney-client relationship. See Sullivan v. Dunne, 198 Cal. 183, 244 P. 343, 346 (1926) ; Evans v. York, 217 S.W.2d 749, 751 (Ct.App.Mo. 1949) ; Merritt v. Merritt, 27 App.Div. 208, 50 N.Y.S. 604, 605-608 (1898). See also Jackson v. Hall, 139 Kan. 832, 836, 32 P.2d 1055, 1057 (1934) ; Lewis v. Commissioner of Banks, 286 Mass. 570, 575, 190 N.E. 790, 791 (1934) ; Restatement (Second) of Agency § 122(1) (1958). Cf. Kimmie v. Terminal R. Ass’n, 344 Mo. 412, 126 S.W.2d 1197, 1200 (1939).
  . A physically and mentally-able litigant bears obligation to respond to an effort by his adversary to obtain deposition-discovery of unprivileged information relevant to the subject matter in suit. Fed.R.Civ.P. 30(a), 36(b).
  . See Bodnar v. Bodnar, 441 F.2d 1103, 1104 (5th Cir.), cert, denied, 404 U.S. 913, 92 S.Ct. 232, 30 L.Ed.2d 186 (1971). See also Smith v. United States, 174 F.Supp. 828 (S.D.Cal.), appeal dismissed, 272 F.2d 228 (9th Cir. 1959), cert, denied, 362 U.S. 954, 80 S.Ct. 868, 4 L.Ed.2d 871 (1960).
  . Will v. United States, supra note 7, 389 U.S. at 96, 88 S.Ct. at 274, 19 L.Ed.2d 305. See also 28 U.S.C. §§ 1291, 1292 (1970) ; Cobbledick v. United States, 309 U.S. 323, 326, 60 S.Ct. 540, 84 L.Ed. 783 (1940). “This general policy against piecemeal appeals takes on added weight in criminal cases,” Will v. United States, supra note 7, 389 U.S. at 96, 88. S.Ct. at 274, but undeniably the policy retains its potency in civil litigation.
  . Will v. United States, supra note 7, 389 U.S. at 104, 88 S.Ct. at 278, quoting Bankers Life & Cas. Co. v. Holland, supra note 7, 346 U.S. at 382, 74 S.Ct. 145, 98 L.Ed. 106.
  . Parr v. United States, 351 U.S. 513, 520 521, 76 S.Ct. 912, 917, 100 L.Ed. 1377 (1956). Accord, Bankers Life & Cas. Co. v. Holland, supra note 7, 346 U.S. at 382-383, 74 S.Ct. 145; Ex parte Fahey, supra note 8, 332 U.S. at 260, 67 S.Ct. 1558, 91 L.Ed. 2041; Roche v. Evaporated Milk Ass’n, supra note 7, 319 U.S. at 25, 30, 63 S.Ct. 938, 87 L.Ed. 1185.
  . Bankers Life & Cas. Co. v. Holland, supra note 7, 346 U.S. at 385, 74 S.Ct. 145; Ex parte Fahey, supra note 8, 332 U.S. at 260, 67 S.Ct. 1558.
  . Compare English v. Cunningham, 108 U. S.App.D.C. 356, 357, 282 F.2d 839, 840 (1960) ; Pauls v. Secretary of Air Force, 457 F.2d 294, 298 (1st Cir. 1972) ; American Express Warehousing, Ltd. v. Trans-america Ins. Co., 380 F.2d 277, 281-282 (2d Cir. 1967) ; Borden Co. v. Sylk, 410 F.2d 843, 845, 846 (3d Cir. 1969) ; Gosa v. Securities Investment Co., 449 F.2d 1330, 1332-1333 (5th Cir. 1971) ; Zalatuka v. Metropolitan Life Ins. Co., 108 F.2d 405, 406-407 (7th Cir. 1939). There are exceptions, not applicable here, to the rule of nonappeala-bility, E. g., Westinghouse Elec. Corp. v. City of Burlington, 122 U.S.App.D.C. 65, 68-69, 351 F.2d 762, 765-766 (1965) ; Diaz v. Southern Drilling Corp., 427 F.2d 1118, 1122-1123 (5th Cir.), cert, denied, Trefina A. G. v. United States, 400 U.S. 878, 91 S. Ct. 118, 27 L.Ed.2d 115 (1970).
  . American Express Warehousing, Ltd. v. Transamerica Ins. Co., supra note 27, 380 F.2d at 283-284; Belships Co., Ltd. Skibs A/S v. Republic of France, 184 F.2d 119 (2d Cir. 1950) ; Bank Line, Ltd. v. United States, 163 F.2d 133, 136, 137 (2d Cir. 1947) ; Byram Concretanks, Inc. v. Meaney, 286 F.2d 170, 171 (3rd Cir. 1961) ; National Bondholders Corp. v. McClintic, 99 F.2d 595, 598-599 (4th Cir. 1938) ; In re Illinois Cent. R.R., 192 F.2d 465, 466 (5th Cir. 1951) ; Chemical § Indus. Corp. v. Druffel, 301 F.2d 126, 129 (6th Cir. 1962) ; Fisher v. Delehant, 250 F.2d 265, 269-270 (8th Cir. 1957) ; Belfer v. Pence, 435 F.2d 121, 122-123 (9th Cir. 1970) ; Paramount Film Distrib. Corp. v. Civic Center Theatre, 333 F.2d 358, 360-361 (10th Cir. 1964)See also C. Wright, The Doubtful Omniscience of Appellate Courts, 41 Minn.L.Rev. 751, 775-76 (1957) ; P. Carrington, The Power of District Judges and the Responsibility of Courts of Appeal, 3 Ga.L.Rev. 507, 513 (1969).
  See, however, Los Angeles Brush Mfg. Corp. v. James, 272 U.S. 701, 47 S.Ct. 286, 71 L.Ed. 481 (1927), and Ex parte Uppercu, 239 U.S. 435, 36 S.Ct. 140, 60 L.Ed. 368 (1915), in each of which the Supreme Court ordered a writ of mandamus directed to a district court in the exercise of the power it formerly possessed to issue “writs of mandamus in cases, . . . warranted by the principles and usages of law, to any courts appointed . . . under the authority of the United States.” Judiciary Act of 1789, 1 Stat. 81; Act of March 3, 1911, ch. 231, 36 Stat. 1156. This power continued until passage of the Act of June 25, 1948, ch. 646, 62 Stat. 944, 28 U.S.C. § 1651 (1970), by which the authority of all federal courts is now limited to “writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principles of law” (emphasis supplied). See In re Josephson, 218 F.2d 174, 177-179 (1st Cir. 1954). As that case warns,
  [D]ecisions of the Supreme Court of the United States, at least prior to 1948, supporting the issuance, by that Court, of a writ of mandamus directed to a lower federal court, may not safely be relied upon by an intermediate court of appeals as authority for the issuance by the latter court of a writ of mandamus directed to a district court within the circuit. The reason is that the Supreme Court might have been exercising a different sort of power from the strictly auxiliary power given to us under the all writs section.
  218 F.2d at 179 (emphasis in original). See also La Buy v. Howes Leather Co., 352 U.S. 249, 265-266, 77 S.Ct. 309, 1 L.Ed.2d 290 (1957) (dissenting opinion).
  . We recognize that petitioner’s arguments encompass the contention that the rulings complained of impinged on Fed.R.Civ.P. 17(c) and 35(a). See notes 2, 16, supra. While a pattern of noncompliance with the federal rules may warrant an invocation of mandamus, La Buy v. Howes Leather Co., supra note 28, 352 U.S. at 257-258, 77 S.Ct. 309; see also Will v. United States, supra note 7, 389 U.S. at 99-100, 102-104, 88 S. Ct. 269; Los Angeles Brush Mfg. Corp. v. James, supra note 28, 272 U.S. at 706, 47 S.Ct. 286; cf. McCullough v. Cosgrave, 309 U.S. 634, 60 S.Ct. 703, 84 L.Ed. 992 (1940), the Court has made it clear that La Buy “is simply inapposite where there is no showing of a persistent, disregard of the federal rules.” Will v. United States, supra note 7, 389 U.S. at 104 n. 14, 88 S.Ct. at 278.
  We are advertent, too, to Schleganhauf v. Holder, supra note 3, where the Court held that mandamus was appropriately used to review a district court order subjecting a defendant in a civil case to physical and mental examinations. The Court rested its holding on the presence of “the basic, undecided question of whether a district court could order the mental or physical examination of a defendant,” 379 U.S. at 110, 85 S. Ct. at 238, 13 L.Ed.2d 152, and, quite significantly, stated:
  This is not to say, however, that, following the setting of guidelines in this opinion, any future allegation that the District Court was in error in applying these guidelines to a particular case makes mandamus an appropriate remedy. The writ of mandamus is not to be used when ‘the most that could be claimed is that the district courts have erred in ruling on matters within their jurisdiction.’ Parr v. United States, 351 U.S. 513, 520, 76 S.Ct. 912, 917, 100 L.Ed. 1377; see Bankers Life & Casualty Co. v. Holland, supra, at 382. 379 U.S. at 112, 85 S.Ct. at 239. See also Will v. United States, supra note 7, 389 U. S. at 104-105 n. 14, 88 S.Ct. 269.
  . Will v. United States, supra note 7, 389 U.S. at 104, 88 S.Ct. 269; Schleganhauf v. Holder, supra note 3, 379 U.S. at 112, 85 S.Ct. 234; Parr v. United States, supra note 25, 351 U.S. at 520-521, 76 S.Ct. 912; Roche v. Evaporated Milk Ass’n, supra note 7, 319 U.S. at 30, 63 S.Ct. 938. See also note 29, supra.
  . Compare Texaco, Inc. v. Borda, 383 F.2d 607, 608-610 (3d Cir. 1967) (order denying leave to depose 71-year-old witness) ; Har-tley Pen Co. v. United States Dist. Ct., 287 F.2d 324, 328-332 (9th Cir. 1961) (order requiring disclosure of trade secrets).
  . Investment Properties Int’l, Ltd. v. IOS Ltd., 459 F.2d 705, 707, 708 (2d Cir. 1972) (order vacating notices of taking of depositions, virtually precluding discovery of facts on which jurisdiction and standing depended). Compare discussion in text supra at notes 13-19.
  . Compare United States v. Hemphill, 369 F.2d 539, 543-544 (4th Cir. 1966) (risk of contempt citation).
  . Roche v. Evaporated Milk Ass’n, supra note 7, 319 U.S. at 30, 63 S.Ct. at 943. Accord, Bankers Life & Cas. Co. v. Holland, supra note 7, 346 U.S. at 382-383, 74 S.Ct. 145, 98 L.Ed. 106; United States Alkali Export Ass’n v. United States, 325 U.S. 196, 202-203 (1945). See also Will v. United States, supra note 7, 389 U.S. at 97 n. 5. “In strictly circumscribing piecemeal appeal, Congress must have realized that in the course of judicial decision some interlocutory orders might be erroneous.” Bankers Life & Cas. Co. v. Holland, supra note 7, 346 U.S. at 383, 74 S.Ct. at 148.
  . Will v. United States, supra note 7, 389 U.S. at 107, 88 S.Ct. at 280, 19 L.Ed.2d 305. Accord, Ex parte Fahey, supra note 8, 332 U.S. at 259, 67 S.Ct. 1558.
  . Ex parte Fahey, supra note 8, 332 U.S. at 260, 67 S.Ct. at 1559. Accord, Will v. United States, supra note 7, 389 U.S. at 107, 88 S.Ct. 269; Parr v. United States, supra note 25, 351 U.S. at 520, 76 S.Ct. 912.