A federal appellate court has ordered an army specialist and her attorney to show cause why they should not be sanctioned for bringing a frivolous suit accusing former Vice President Dick Cheney, former Secretary of Defense Donald Rumsfeld and former Chairman of the Joint Chiefs of Staff Richard Myers of orchestrating the Sept. 11, 2001, terror attacks.

In Gallop v. Cheney, 10-1241, a panel of the U.S. Court of Appeals for the Second Circuit yesterday affirmed the dismissal of the case by Southern District Judge Denny Chin, and gave April Gallop and her attorney, William W. Veale, 30 days to file a brief explaining why they should not be jointly and severally liable for $15,000 in sanctions.

“After a de novo review, we have no hesitation in concluding that the District Court correctly determined that the few conceivably ‘well-pleaded’ facts in Gallop’s complaint are frivolous,” Judge José A. Cabranes wrote for the panel, which included Judges Ralph K. Winter Jr. and John M. Walker Jr.

“While, as a general matter, Gallop or any other plaintiff certainly may allege that the most senior members of the United States government conspired to commit acts of terrorism against the Untied States, the courts have no obligation to entertain pure speculation and conjecture,” he said.

Mr. Veale, of Walnut Creek, Calif., said yesterday that while he planned to submit a brief within 30 days as ordered, he did not have new facts or arguments.

“You would think it’s a tremendous opportunity to basically show everything we have, but we’ve already shown everything we have,” he said.

Mr. Veale also said he and his client would ask for a rehearing en banc. “We’re gonna be fighting it all the way,” he said.

Earlier this month, Mr. Veale had asked that Judge Walker, a cousin of former President George W. Bush, be removed from the case. The court denied this request.

The lawsuit brought by Ms. Gallop in December 2008 claims that shortly after she and her infant son arrived for her work at the Pentagon on Sept. 11, 2001, there was an explosion that caused the walls and ceiling around her to collapse and her to lose consciousness. When she regained consciousness, according to the complaint, she made her way out of the blown-out front of the Pentagon, but saw no sign of an airplane having struck the building.

Ms. Gallop alleges that the Pentagon was actually destroyed by explosive charges inside the building “and/or a missile of some sort.” She alleges that the hijacked American Airlines Flight 77 was flown low over the Pentagon and then crashed “someplace else,” possibly by remote control.

Ms. Gallop acknowledges in her suit that hijacked planes “evidently” did crash into the World Trade Center towers, and that a fourth plane was hijacked and crashed in Pennsylvania. However, she claims that the planes were either operated by the defendants through remote control or hijacked by Muslim extremists acting as “dupes or patsies” for the defendants. She allowed that the Muslim extremists may also have developed the plan themselves, but that it was then co-opted by U.S. government officials.

In support of these theories, Ms. Gallop alleges that government officials, led by the defendants, deliberately allowed the hijackers to enter the U.S. and plan their attack, and that they stopped the planes from being intercepted by military fighters on Sept. 11.

Ms. Gallop is seeking damages for continuing pain and suffering and medical costs for her and her son.

Judge Chin dismissed the case in March 2010. He said that most of the complaint was purely speculative, “not plausible” and “the product of cynical delusion and fantasy.”

The Second Circuit agreed with Judge Chin, and added that because the complaint does not have a coherent narrative about how exactly the alleged conspiracy worked, it “utterly fails to set forth a consistent, much less plausible, theory for what actually happened that morning in Arlington, Virginia.”

The panel also noted that Ms. Gallop had filed a previous suit accusing American Airlines of facilitating the attacks and maintaining that Flight 77 did in fact hit the Pentagon. That suit was also dismissed.

“While Gallop’s counsel asserted at oral argument that Gallop’s inconsistent claims could be explained by the emergence of new evidence since her previous submissions, he did not identify any” such evidence, Judge Cabranes notes. “We therefore do not know whether Gallop’s reconsideration of the events of September 11, 2001, is the product of new evidence or of new counsel.”

Mr. Veale said that in oral arguments he had pointed to new evidence involving the “scrubbing” of radar tracks around the Pentagon at the time of the attacks.

While the defendants did not seek sanctions, the Second Circuit panel noted that it believed that the $15,000 sanction was warranted because the lawsuit clearly had no chance of success and Mr. Veale should never have filed it, even if Ms. Gallop wanted him to.

The U.S. government officials were represented by Southern District Assistant U.S. Attorneys Alicia M. Simmons and Benjamin H. Torrance.