U.S. District Judge Sam Sparks on Monday upheld the jurisdiction of USADAto pursue its case against Armstrong, noting that the agency's authorization stemmed from an act of Congress and that its arbitration process does not violate Armstrong's right to due process.

Sparks said the court "should not interfere with an amateur sports organization's disciplinary procedures unless the organization shows wanton disregard for its rules, to the immediate and irreparable harm of a plaintiff, where the plaintiff has no other available remedy."

Sparks, who heard the case in Armstrong's hometown of Austin, Texas, ruled that the cyclist has not suffered such harm in this case. He noted that USADA's arbitration rules follow the guidelines of the American Arbitration Association, are "sufficiently robust" and allow for further appeals if desired.

USADA confirmed that Armstrong now faces a Thursday deadline to decide whether he will choose arbitration or accept harsh sanctions, including a likely lifetime ban and the stripping of his seven titles in the Tour de France. An additional factor for Armstrong is whether a lifetime ban would prevent him from competing in triathlons, his current sport.

Armstrong also could appeal Sparks' ruling, a move that could push back the deadline. It also would seem unlikely to achieve a different result, as Sparks' decision squared solidly with past court rulings. USADA has never lost a court challenge of its jurisdiction.

"We are reviewing the Court's lengthy opinion and considering Mr. Armstrong's options at this point," Tim Herman, an attorney for the cyclist, said in a statement.

USADA CEO Travis Tygart said in a statement that the agency was pleased with the court's decision.

"The rules in place have protected the rights of athletes for over a decade in every case USADA has adjudicated and we look forward to a timely, public arbitration hearing," should Armstrong choose, the statement said.

Even as USADA claimed an across-the-board legal victory, Sparks' ruling included a warning to the agency regarding its actions in the case, calling the charging letter it sent Armstrong "woefully inadequate."

Sparks said he was persuaded by USADA's counsel that Armstrong would receive plenty of advance notice with specifics on the charges against him should he opt for arbitration. If not, "and it is brought to this Court's attention in an appropriate manner, USADA is unlikely to appreciate the result," the judge wrote.

Sparks also questioned USADA's pursuit of charges against Armstrong beyond its own eight-year statute of limitations, and lamented the infighting among cycling groups over the Armstrong case. And he wrote that if USADA is promising lesser sanctions to other riders who cheated in exchange for their testimony against Armstrong, "it is difficult to avoid the conclusion that USADA is motivated more by politics and a desire for media attention than faithful adherence to its obligations…"

But the judge said it all added up to the same conclusion: The court did not have cause to intervene in advance of a long-established arbitration process, which Armstrong agreed to when he competed in licensed events.

"Despite its many misgivings about USADA's conduct leading up to and during this case, the Court is bound to honor Armstrong's agreement," Sparks ruled,

Herman seized upon Sparks' comments about USADA in the ruling.

"Judge Sparks' opinion confirms what we have said all along. Among other things, the Court confirmed that 'USADA's conduct raises serious questions about whether its real interest in charging Armstrong is to combat doping, or if it is acting according to less noble motives,' " Herman said.

The drama began in June, when USADA filed charges against Armstrong and five other members of the U.S. Postal Service cycling team. In the letter of charges, USADA outlined that Armstrong and the others were part of a sophisticated conspiracy in which they used banned drugs and blood transfusions to gain an advantage.

Each was given a choice: They could fight the charges in arbitration or accept sanctions. Three opted for arbitration. Two others declined to fight and were given lifetime bans.

Faced with being stripped of his titles, Armstrong filed a federal lawsuit against USADA in July that argued the agency lacked jurisdiction over him and that it denied him due process.

In hearing arguments on the suit in Austin, Texas, on Aug. 10, Sparks hinted that he had questions about whether the court should intervene, pointing out that even the challenge of USADA's jurisdiction could be decided in arbitration. He asked Armstrong's attorney, Tim Herman, why the federal court should get involved when such disputes are almost always decided in arbitration.

Armstrong claimed that the arbitration process was "rigged" in USADA's favor. The agency has a 58-2 record in arbitration — a history the agency attributes to the strength of the cases against the accused.

On Monday, Sparks rejected Armstrong's attempt to claim "speculative injury."

The court "declines to assume either the pool of potential arbitrators, or the ultimate arbitral panel itself, will be unwilling or unable to render a conscientious decision based on the evidence before it," Sparks wrote.

If Armstrong decides to pursue arbitration, each side would nominate a member of the three-person panel, with the third member being agreed to by both parties. Or Armstrong could request a single arbitrator.