From department d’oh : a mistrial was declared earlier today in the federal perjury trial of Roger Clemens, after the jury was shown evidence previously deemed inadmissible by US District Court Judge Reggie Walton.  From the New York Times’ Juliet Macur :

“He is entitled to a fair trial and, in my view, he can’t get it now, and that was caused by the government,” the judge, Reggie Walton said.

The prosecutors left the courthouse without speaking to reporters. Judge Walton set a hearing date of Sept. 2 for them to reveal if they plan to retry the case, which was only two days into testimony. Normally when a mistrial is called, even further into a trial, double jeopardy is not an issue, some legal experts said.

Judge Walton abruptly stopped the trial and scolded the prosecution for playing a videotape of the 2008 Congressional hearings on performance-enhancing drug use in baseball. The part of the tape that worried him included comments made by Representative Elijah E. Cummings, a Maryland Democrat, in which he described Andy Pettitte, Clemens’s onetime best friend and teammate, as being credible. Pettitte was expected to be one of the star witnesses for the government in this trial.

The prosecution also played for the jury a part of the Congressional hearings in which Cummings read an affidavit from Andy Pettitte’s wife, Laura. In the affidavit, she said that her husband had told her about a conversation he had with Clemens about Clemens’s use of human growth hormone.

Judge Walton ruled last week that Laura Pettitte’s testimony would be barred from the trial, unless it was needed for rebuttal evidence when Andy Pettitte was on the stand.

“A mistrial like this is a rare event in federal courts, Deliberate defiance of a judge’s order by federal prosecutors is even rarer,” mused ESPN.com’s Lester Munson.  “But this combination of rare events could allow Clemens to walk away from a massive investigation and prosecution that seemed likely to send him to prison.” And with that, any threat that Clemens’ frosted tips might be messed up in a country club jail, might, unfortunately, be out the window.