How do you pick a jury of 12 Washingtonians to serve in a high-profile perjury trial of an iconic baseball star accused of lying to Congress about his use of performance-enhancing drugs?

Here’s how: First, a federal judge leads off with an 82-item questionnaire with carefully crafted queries that ask prospective jurors about their backgrounds, the law, baseball and Congress. Next up, federal prosecutors and defense attorneys sling their own questions, hoping to probe the psyches of D.C. residents for biases.

Finally, they mull over such responses as: Baseball players scratch themselves. A lot of athletes take steroids. Lawmakers lie. And, who is Roger Clemens, anyway?

Citing a gag order issued by U.S. District Judge Reggie B. Walton, federal prosecutors and defense attorneys in the case of Clemens, a 48-year-old former All-Star pitcher, declined to discuss their pretrial strategies. Outside experts, however, said the questions posed by the judge and attorneys reveal their belief that jurors’ feelings about sports and Congress could prove critical in shaping a verdict.

“Jury selection is more art than science,” said Thomas C. Green, a District-based defense lawyer with no connection to the Clemens case. “There are lots of mental gymnastics in this.”

Charged with perjury, obstructing Congress and making false statements, Clemens is accused of lying when he testified before a House committee in 2008 that he had never taken performance-enhancing drugs.

His trainer, Brian McNamee, testified at the same hearing that he injected Clemens with steroids and human growth hormone with the pitcher’s knowledge.

The trial marks the second recent prosecution of a legendary baseball player accused of lying about his use of performance-enhancing drugs during his career. In April, the trial of slugger Barry Bonds concluded in a California federal court with the player convicted of obstruction of justice after the jury couldn’t reach a verdict on perjury charges.

Clemens has joined a list of players once considered surefire Hall of Fame inductees — such players as Bonds, Mark McGwire and Rafael Palmeiro, among others — whose associations with performance-enhancing drugs, whether admitted or alleged, have marred their sporting legacies and Major League Baseball’s image.

For now, the focus is on Clemens, who was indicted last summer. The jury selection process, which began Wednesday with 50 men and women, will play out over at least two more days. Walton, who has a reputation for being thorough in jury selection, has already chosen 18 people to be part of a final pool of 36 potential jurors.

Eleven others have been cut. Prosecutors and defense attorneys will use jurors’ answers to help decide who else to strike to get a final 12-member jury, which will hear evidence over a month or so.

In many ways, the importance of these questions and answers won’t be fully known until a verdict is reached: Will a juror who is a huge baseball fan be more sympathetic to Clemens or the government? If someone thinks lying to Congress is a serious crime, is he or she likely to convict?

Until then, attorneys must make their best guesses about what the jurors’ statements mean. And although many of the questions are standard fare in federal criminal trials — Are jurors sure they can render a fair verdict? Do they know a defendant is innocent until proven guilty? Do they realize defendants don’t have to testify in their own defense? — they can be useful, too. One prospective juror was excused when she said she thought Clemens had to produce evidence of his innocence.

And in a city known for its news obsession, Walton wanted to ensure that jurors hadn’t been overly exposed to media reports about the case.

That isn’t an issue in most trials, but Clemens allegedly committed his crime on Capitol Hill before a national television audience.

At least two jurors said they had watched the hearings, or parts of them; a few had read news accounts. A good number said they had no idea Clemens had testified before Congress; some said they didn’t even know the seven-time Cy Young Award winner had been a ballplayer.

“If he was sitting there, I would not know who he was,” one prospective juror said. He was sitting there: Clemens, nicknamed “Rocket” when he played for the Boston Red Sox, Toronto Blue Jays, New York Yankees and Houston Astros over 23 years, was 20 feet away.

In response to questions about whether Congress should investigate the use of performance-enhancing drugs, potential jurors expressed mixed opinions. Many said they believed that Congress has the responsibility to look into the matter. Others disagreed.

“Given all the problems the country faces, it wouldn’t have been high on my list of priorities,” said a chief financial officer at an accounting firm who was later dismissed from the jury pool.

Another was more blunt. “Even members of Congress have lied to Congress, and they have not been prosecuted,” the man said. He, too, was excused.

Federal prosecutors Steven Durham and Daniel Butler asked many potential jurors to rank their passions for sports and baseball on scales of one to 10. Several called themselves avid baseball fans: One liked the Baltimore Orioles and San Francisco Giants, while another — surprisingly, perhaps — said he favored both the Philadelphia Phillies and Washington Nationals.

One woman, a former lawyer and writer, called herself a “diehard” Nationals fan. She seemed eager to serve: “I can contribute by making sure everyone is focused,” she said.

Others were less enthusiastic about baseball. “I couldn’t imagine spending money to watch a sport where guys scratch themselves and spit a lot,” a public-relations consultant said.

Another potential juror recalled a visit to Nationals Park — for the opera.

“My husband is a sports fan, so I often listen to sports news whether I want to or not,” she said. “I have little interest in sports. It simply isn’t of paramount importance to me.”

But this is Washington, where conversations about sports inevitably turn to football.

When one prospective juror, a civilian manager with the Marine Corps, said she didn’t follow baseball but was a huge Redskins fan, defense attorney Rusty Hardin took no chances: In a smooth Texas drawl, he quickly pointed out that Clemens lives in Houston, not Dallas, home of the dreaded Cowboys.