The perjury trial of Roger Clemens is slated to open Wednesday with a jury of 10 women and two men sitting in judgment of the former star pitcher accused of lying to Congress about using performance-enhancing drugs.

Federal prosecutors and Clemens’s defense lawyers on Tuesday winnowed the jury pool down to 12 from 36 candidates, ending four days of intense questioning of more than 50 Washingtonians about their backgrounds — down to their favorite sports teams.

Among the jurors who made the final cut were a retired painter at the Smithsonian Institution, a letter carrier, a part-time health aide, a lawyer for the Federal Communications Commission and a yoga instructor. Four others, two men and two women, were chosen as alternates for the trial, which is expected to last perhaps a month.

During the final round of the selection process Tuesday afternoon, Clemens watched quietly as his lawyers huddled over notes and discussed prospective jurors in whispers before striking them from the final panel. Federal prosecutors and FBI agents conducted their own session just feet away.

Before dismissing jurors for the day, U.S. District Judge Reggie B. Walton urged them not to discuss the case or do their own research on it. The trial, which has already drawn intense media attention, will officially open Wednesday with opening statements.

Charged with perjury, making false statements and obstruction of Congress, Clemens is accused of lying to a House committee in 2008 when he testified that he had never taken performance-enhancing drugs during his playing days.

Clemens’s former trainer, Brian McNamee, testified before the committee that he had actually injected Clemens with steroids and human growth hormone with the pitcher’s knowledge. The House Committee on Oversight and Government Reform referred the matter to the Justice Department, and Clemens was indicted by a grand jury last year. McNamee is expected to be the prosecution’s star witness.

During a brief hearing Tuesday morning, defense lawyers signaled they will argue that Clemens cannot be convicted of obstructing Congress because the House committee overstepped its authority when it held a hearing pitting the pitcher against his trainer.

In essence, the attorneys argue, the hearing was a show trial that had nothing to do with pending legislation of any kind, and Clemens cannot be convicted of obstructing Congress if it was not exercising its “due and proper” power, as alleged in the indictment.

Defense lawyers are also expected to raise questions about whether Clemens’s statements to a House committee were “material” to any congressional action. The only official action taken by the committee after the hearings was to refer the matter to the Justice Department for a possible perjury prosecution.

Tuesday afternoon, Walton said that he was disturbed that relatives of Clemens had taken to the blogosphere to attack witnesses and others tied to the case. He was apparently referring to a New York Daily News story that pointed out that Clemens’s sister had attacked McNamee on Twitter.

The judge has issued a gag order forbidding anyone associated with the case — prosecutors, defense lawyers, Clemens and witnesses — to discuss it with the media. But his order does not apply to the former pitcher’s relatives — unless, perhaps, Clemens or his lawyers directed the family members to conduct the Twitter campaign.

Rusty Hardin, Clemens’s attorney, said he would look into the matter.