By Ian Simpson

WASHINGTON (Reuters) - Roger Clemens' lawyer rejected federal charges of perjury against the former pitching star, saying on Tuesday Clemens is opposed to steroid use and simply told the truth in denying he had used them.

"You are sitting in judgment to decide whether it is a crime to deny a crime," attorney Rusty Hardin told jurors in his opening statement at the trial of Clemens, who is charged with lying to Congress in testimony concerning performance-enhancing drugs.

Use of steroids and human growth hormone "was total anathema, totally against everything he stood for," Hardin said.

Hardin said Clemens' former trainer, who is expected to testify that the baseball star used performance-enhancing drugs, is a liar. He said Clemens became one of the best pitchers of his era by following a rigorous conditioning program - not by taking steroids.

"The only thing he wanted to do was be a baseball player and be the best he could," Hardin said.

Use of steroids and human growth hormone "was total anathema, totally against everything he stood for," Hardin said.

Clemens, 49, who won the Cy Young Award a record seven times as his league's best pitcher, is being tried for a second time on charges of lying to the House of Representatives Committee on Oversight and Government Reform in 2008 about whether he used performance-enhancing drugs.

Clemens first went on trial last July. U.S. District Judge Reggie Walton declared a mistrial because prosecutors showed jurors a video clip that included material the judge had banned from the case unless it was raised by Clemens' defense team.

Hardin's opening statement on Tuesday was meant to counter charges by prosecutors that Clemens had covered up his steroid use.

In his opening statement on Monday, U.S. Attorney Steven Durham said proof that Clemens took steroids includes needles and bloody swabs that independent tests have shown contain the former elite pitcher's DNA and performance-enhancing drugs.

Hardin struck back by telling jurors that Clemens has never tested positive for steroids or showed any sign of their use, such as increased bulk. "This case all along has been only about one man's persistence in trying to clear his name against all odds," he said.

Clemens faces one count of obstruction of Congress, three counts of making a false statement and two counts of perjury in a trial that may run as long as six weeks. If convicted, he faces a maximum prison term of 30 years, although under federal sentencing guidelines he would most likely get 15 to 21 months.

Hardin took aim on Tuesday at Brian McNamee, who had been Clemens' trainer and is now expected to be a key prosecution witness. He likely will testify that he injected Clemens with anabolic steroids in 1998, 2000 and 2001 and with human growth hormone in 2000.

Calling McNamee a liar, Hardin said federal authorities would be unable to show any corroboration for McNamee's claims despite an investigation that included 268 interview reports and the use of 103 federal agents and eight assistant U.S. attorneys.

Clemens career "never changed" during the years of alleged steroid use, Hardin told the jury. "It was what it was before Brian McNamee, it was what it was during Brian McNamee, it was what it was after Brian McNamee."

Clemens played for Boston, Toronto, Houston and the New York Yankees in a career that ran from 1984 to 2007.

(Editing by Paul Thomasch and Bill Trott)