We saw it happen in the John Stagliano obscenity trial. Is it just our imagination, but are federal prosecutors truly this incompetent in procedural matters?

Washington, DC — from www.latimes.com - The judge in Roger Clemens' perjury trial declared a mistrial Thursday.

U.S. District Court Judge Reggie Walton declared the mistrial because the prosecution presented inadmissible and prejudicial evidence to the jury.

The trial was only in its second day, having begun Wednesday with opening statements after jury selection lasted a week.

Clemens was charged with three counts of making false statements, two counts of perjury and one count of obstruction of Congress. He pleaded not guilty last August to charges he lied to Congress about his alleged use of performance enhancing drugs.

According to the New York Times, the critical moment came when prosecutors played video footage of the 2008 Congressional hearings on PED usage in baseball.

The report said the footage showed Rep. Elijah Cummings reading an affidavit from the wife of Andy Pettitte, Clemens' former teammate and friend. However, Walton had previously ruled Laura Pettitte's testimony inadmissible.

The footage also showed Cummings remarking on the credibility of Andy Pettitte, expected to be a witness at the trial, according to the report.

Walton immediately stopped trial proceedings as the video played, pausing it as a quote of Laura Pettitte's affidavit was on the screen, the Times reported.

The part of Pettitte's affidavit that remained on screen for the jury to see included the statment that "Andy told me that he had had a conversation with Roger Clemens in which Roger admitted to him using human growth hormone," the report said.

Walton eventually granted the defense's mistrial motion and will hear on September 2 if the government plans to retry the case, the report said.