WASHINGTON (Reuters) - The perjury trial of Roger Clemens begins on Wednesday with the selection of 12 jurors charged with deciding if the former baseball star lied when he said he never took drugs to boost his pitching as he aged.

Clemens, 48, was indicted a year ago on charges he gave false statements to a congressional committee investigating steroid use in baseball, perjured himself under oath and obstructed the lawmakers' inquiry into widespread drug use that has scarred the sport.

Clemens, winner of seven Cy Young Awards, more than any other pitcher, has denied ever taking human growth hormones or steroids or lying to Congress. If he is convicted, federal sentencing guidelines call for up to 21 months in prison, though the maximum penalty is 30 years.

The charges stem from an independent report commissioned by Major League Baseball that found many players had used drugs, prompting the House of Representatives' Oversight Committee to hold hearings on the study's conclusions.

The trial, expected to last at least a month, will pit the word of Clemens against that of two former close associates who are expected to be star witnesses -- former trainerBrian McNamee and teammate Andy Pettitte.

Clemens' defense team argues that his primary accuser, McNamee, is a habitual liar and trumped up the allegations and evidence about drug use to distract from his own legal problems, stemming from a 2001 sexual assault investigation.

McNamee has acknowledged he lied to investigators looking into the sexual assault case but he was never charged.

Prosecutors have also indicated they have evidence -- needles, swabs and DNA -- that will prove Clemens used performance-enhancing drugs.


But Clemens' chief defense attorney, Rusty Hardin, said on Tuesday the physical evidence is false.

"Physical evidence has been fabricated and manipulated by Mr. McNamee," he told the court during arguments about what testimony may be given by witnesses.

The judge overseeing the trial indicated he would not allow other players to talk about their use of steroids and dealings with McNamee because it could unfairly connect such interactions with Clemens.

But prosecutors hope to also show the jurors that Clemens talked about using human growth hormones to Pettitte, though Clemens has repeatedly said his former teammate "misheard" and "misremembers" the conversation.

The pitcher's wife, Debra, is also expected to testify.

His defense team has urged the judge to ask the jury to only convict him if they believe he had intended to lie to the House committee that conducted hearings into steroid use.

There had been talk of a plea deal before Clemens was indicted but negotiations never went anywhere.

Clemens is the latest baseball player to go on trial for lying about whether he used drugs to boost his performance.

In April, a jury convicted retired San Francisco Giants slugger Barry Bonds on one obstruction charge but was unable to decide whether he lied about steroid use. In 2009 infielder Miguel Tejada pleaded guilty to lying to Congress about doping in baseball.

Clemens started his career in 1984, at age 21, and pitched until he was 45, amassing statistics that would have guaranteed entry to the Hall of Fame if not for the drug scandal.

Pitching for four teams -- the New York Yankees, Boston Red Sox, Toronto Blue Jaysand Houston Astros -- he racked up a 354-184 career won-loss record and is one of four pitchers to strike out over 4,000 batters.