Opinion for the Court filed by Chief Judge HARRY T. EDWARDS.
Dissenting opinion filed by Circuit Judge WALD.
HARRY T. EDWARDS, Chief Judge:Russell Eugene Weston, Jr., the appellant in this case, is charged with the murder of two United States Capitol Police Officers and the attempted murder of a third. In this appeal, Weston seeks to challenge an order of the District Court requiring him to undergo a competency examination to be conducted by a psychiatrist suggested by the Government. Weston claims that he can only be examined by a psychiatrist of his own choosing or by a neutral doctor appointed by the trial court. However, Weston never suffered the situation of which he complains, because he repeatedly refused to speak to the psychiatrist who had been appointed at the suggestion of the Government. Due to Weston’s refusal to undergo an examination by a Government psychiatrist, the prosecution finally withdrew its objection to a finding of incompetency and Weston was committed for treatment to restore competency pursuant to 18 U.S.C. § 4241(d) (1994). As a result, the order that Weston challenges was never carried out and it is no longer in effect. Accordingly, we dismiss the appeal as moot.
I. Background
On October 9, 1998, Russell Weston was indicted for the July 24, 1998 murders of United States Capitol Police Officer Jacob J. Chestnut and Special Agent John M. Gibson, and for the attempted murder of United States Capitol Police Officer Douglas B. McMillan. On October 15, 1998, the Government and the defense filed a joint request pursuant to 18 U.S.C. § 4241 for a mental competency examination of Weston.
The District Court appointed Dr. Sally C. Johnson, the Chief Psychiatrist and Associate Warden of Health Services at the Mental Health Division of the Federal Correctional Institution in Butner, North Carolina (“FCI-Butner”), to conduct an outpatient psychiatric examination of the defendant to assist the court in determining whether the defendant was competent to stand trial. Dr. Johnson spent approximately 20 hours with the defendant, personally administering psychiatric and personality tests to him; she also reviewed numerous medical and mental health records and interviewed family members. Following her examination, Dr. Johnson submitted a report to the District Court and defense counsel under seal. Thereafter, defense counsel consented to a release of the report in unredacted form to the Government. Dr. Johnson concluded that the defendant was presently incompetent to stand trial, but that competency might be restored with extended hospitalization and treatment with anti-psychotic medication.
Concerned by what it perceived to be certain omissions and inconsistencies in Dr. Johnson’s report and in the defendant’s conduct, the prosecutor asked the District Court to compel the defendant to submit to an examination by a mental health expert of the Government’s choosing. By Memorandum and Order filed January 28, 1999, reprinted in Joint Ap*147pendix at 35-60, and modified on February 12, 1999, United States v. Weston, 36 F.Supp.2d 7 (D.D.C.1999), the District Court granted the Government’s motion. The same order also committed the defendant to the United States Medical Center for Federal Prisoners at Springfield, Missouri (“Springfield”) for an examination by another court-selected expert. The examination by the Government doctor was to take place while the defendant was at Springfield.
The defendant was sent to Springfield on February 3, 1999. A staff psychiatrist there, Dr. James Wolfson, was to serve as the court-selected examiner; Dr. Debra DePrato was retained as the Government’s expert. The defendant refused to answer substantive questions posed by Dr. Wolf-son, Dr. DePrato, or other staff members at Springfield, repeatedly stating that he declined to answer questions upon the advice of counsel. Counsel for Mr. Weston states that this behavior was “solely a product of [Weston’s] delusions,” and that Weston has refused to talk to his own attorney on the same grounds. Appellant’s Reply Br. at 4 n.2, 10. In any event, as a result, the doctors were unable to obtain any pertinent information and the District Court ordered that Weston be brought back to Washington, D.C.
On March 3, 1999, the District Court modified its order to permit Dr. Wolfson and Dr. DePrato to examine Weston at the courthouse or at the Correctional Treatment Facility in Washington, D.C., and to allow Dr. DePrato to arrange psychological testing of Weston. However, Weston again refused to cooperate with the doctors.
Weston’s competency hearing was scheduled to take place on April 22, 1999, but on April 9, 1999, in light of Weston’s refusal to cooperate with any further mental examinations and concerned that the case not be delayed any longer than necessary, the Government withdrew its objection to a finding of incompetency based on Dr. Johnson’s original report. On April 22, 1999, the District Court found Weston incompetent to stand trial and committed him for treatment to restore competency pursuant to 18 U.S.C. § 4241(d).
II. Analysis
In this appeal, Weston argues that the District Court lacked the authority to order a competency examination by a doctor chosen by the Government. Weston claims that, under 18 U.S.C. §§ 4241 and 4247(b), competency examinations may be conducted only by mental health experts appointed by the trial court or selected by the defendant. The Government does not contend that it has an absolute right to the appointment of an expert to conduct a competency examination; rather, the Government claims only that it has the right to request, and the District Court has the discretion to grant, a competency examination by a mental health expert suggested by the Government. We need not decide the scope of the disputed statutory provisions, however, because the instant appeal is moot.
The date(s) for the competency examinations at issue have come and gone. Because the defendant refused to speak to the Government’s suggested psychiatrist, no examination ever took place. By withdrawing its objection to a finding of incompetency, the Government also necessarily withdrew its request that the defendant be compelled to submit to an examination by a doctor other than Dr. Johnson. The defendant has been found incompetent to proceed and has been committed for treatment to restore competency pursuant to 18 U.S.C. § 4241(d). In sum, the order that Weston seeks to challenge was never carried out and is no longer in effect.
“[A] federal court has neither the power to render advisory opinions nor ‘to decide questions that cannot affect the rights of litigants in the case before them.’ ” Preiser v. Newkirk, 422 U.S. 395, 401, 95 S.Ct. 2330, 45 L.Ed.2d 272 (1975) (citation omitted). “For that reason, if [ ] event[s] occur *148while a case is pending on appeal that make[ ] it impossible for the court to grant ‘any effectual relief whatever’ to a prevailing party, the appeal must be dismissed [as moot].” Church of Scientology of California v. United States, 506 U.S. 9, 12, 113 S.Ct. 447, 121 L.Ed.2d 313 (1992). That is precisely what has occurred here. Events have transpired such that Weston did not submit to the disputed examination and is no longer subject to any order requiring him to do so.
Weston argues, however, that the case should not be dismissed as moot because it falls within the exception to the mootness doctrine for cases capable of repetition yet evading review. This exception applies if: “(1) the challenged action [is] in its duration too short to be fully litigated prior to its cessation or expiration[;] and (2) there [is] a reasonable expectation that the same complaining party [will] be subject to the same action again.” LaRouche v. Fowler, 152 F.3d 974, 978 (D.C.Cir.1998) (alterations in original) (citing Spencer v. Kemna, 523 U.S. 1, 118 S.Ct. 978, 988, 140 L.Ed.2d 43 (1998)).
We assume, in agreement with the defendant, that the disputed issue is capable of repetition, because Weston might again be ordered to submit to a Government competency examination. First, if the doctors at FCI-Butner ultimately conclude that Weston cannot be restored to competence in the foreseeable future, the prosecution may seek an examination by a Government psychiatrist to challenge that conclusion. Second, even if the doctors at FCI-Butner conclude that Weston has regained competency, Weston may call a number of defense experts to challenge that conclusion and, in that event, the Government may want its own expert to assist in responding to the defense experts. In either event, the District Court may again order a competency examination by a mental health expert suggested by the Government. However, even assuming that the issue surrounding the Government’s asserted right to suggest the appointment of a mental health expert is capable of repetition, this case is nonetheless moot because any further dispute over this issue will not evade review.
Weston argues that an order compelling a defendant to undergo a competency examination by a Government mental health expert is immediately appealable under this court’s decision in United States v. Weissberger, 951 F.2d 392 (D.C.Cir.1991). Weissberger held that an order compelling a 30-day competency evaluation was immediately appealable under the collateral order doctrine, which allows the appeal of orders that might otherwise be viewed as non-final, so long as three conditions are met: the order must “(1) ‘conclusively determine the disputed question,’ (2) ‘resolve an important issue completely separate from the merits of the action,’ and (3) ‘be effectively unreviewable on appeal from a final judgment.’ ” Weissberger, 951 F.2d at 396 (quoting Coopers & Lybrand v. Livesay, 437 U.S. 463, 468, 98 S.Ct. 2454, 57 L.Ed.2d 351 (1978)). There is no doubt that if Weissberger applies in a situation such as the one at hand, then the case is moot. This is because immediate appeal will be available in the future in the event that Weston is again ordered to undergo a competency examination by a Government mental health expert. Thus, the issue would not escape review.
The Government, however, argues that Weissberger is inapposite. In the Government’s view, the court’s determination in Weissberger that the District Court’s order would be effectively unreviewable on appeal after final judgment was based on the loss of liberty associated with the confinement for the competency evaluation ordered in that case, not the intrusion of the examination itself. In this case, the Government argues, Weston has already been held without bail so there is no loss of liberty.
We need not decide the applicability of Weissberger in this case, because, regardless of the availability of immediate appeal, *149the issue raised in this case will not evade review. If Weissberger does apply (so that any future order of a mental examination by a Government doctor is immediately reviewable and, presumably, subject to a stay pending review), then the defendant’s interest in avoiding the intrusion of the examination will be protected. On the other hand, if Weissberger does not apply and the defendant must wait until after his conviction (if any) to obtain review, that result will necessarily reflect the court’s conclusion that the order at issue is not “effectively unreviewable on appeal from a final judgment” and that protecting a defendant from the intrusion associated with a particular medical examination is not, by itself, worth the extra delay and disruption of the criminal trial process.
In sum, because any future order compelling this defendant to undergo a competency examination by a Government psychiatrist will be subject to review, either immediately or following a final judgment, the case is moot.
III. Conclusion
For the foregoing reasons, the appeal is dismissed as moot.
So ordered.