Judge Reggie Walton declared a mistrial in the perjury prosecution of Roger Clemens, after prosecutors presented evidence that the judge previously had excluded in limine. The evidence at issue was a mention of a statement by Andy Pettitte's wife that Andy had told her that Clemens had admitted to him that he had used HGH, apparently in response to Clemens' defense that Pettitte had either misheard or "misremembered" what Clemens told him. The exclusion of the evidence seems like the correct call, particularly if Clemens' defense is that Pettitte misheard; Pettitte repeating what he misheard does not rebut the possibility that he, in fact, misheard. On the other hand, if Clemens' defense was that Pettitte's memory failed, this evidence may have become relevant later in the trial. So there is a nice question whether a mistrial was appropriate at this point over a fairly small piece of credibility evidence that might even have become relevant later
The government now must decide whether to retry the case and Judge Walton has scheduled hearings for later this month and next month to decide whether it can or whether jeopardy has attached (sometimes the case when the government's misconduct causes the mistrial). And perhaps the government will consider whether this all is worth the candle in any event.
Line of the hearing from Judge Walton (who apparently raised his voice throughout): "I think that a first-year law student would know that you can't bolster the credibility of one witness with clearly inadmissible evidence." First-year law students, take note.
Update: Nina Totenberg talked about the ruling on NPR's All Things Considered. From her description, it sounds as if three things triggered the mistrial: 1) Pettitte is a key witness, so this was vouching for a key witness; 2) this is the second time the government had ignored a prior ruling; and 3) when the parties conferred with the judge right after the inadmissible material came out (on the video of the congressional hearing), the government left the video frozen on the improper point showing the hearing and a transcript of what was being said. In other words, during a several-minute sidebar conference, the jurors were staring at the objectionable evidence. Number 3 strikes me as the big one--it's not just that the jury heard inadmissible evidence, but that they were staring at it for several minutes.
Further Update: Last night, I was interviewed about the case on Seattle's KJR Sports Radio.