U.S. District Judge Reggie Walton may have altered the legal strategies of prosecutors and Roger Clemens' attorneys this afternoon when he said that he will probably deny former Yankees players, including Andy Pettitte and Chuck Knoblauch, from discussing any performance-enhancing drugs they received from Brian McNamee, Clemens' former trainer and chief accuser.

In one respect, the denial would be a victory for Clemens, who would like to prevent jurors from inferring that if McNamee supplied steroids to Clemens' former teammates, then McNamee probably did the same with Clemens. Recognizing Clemens' concern, Judge Walton even said that he received cortisone shots from a trainer when he played college football, and that "I would not want to be held responsible for doing something inappropriate based on what that trainer was giving to other people." With jurors unable to hear that McNamee supplied steroids to Clemens' teammates, jurors may be more inclined to believe Clemens that McNamee only provided him legal substances, namely Vitamin B12 and Lidocaine. Clemens' attorneys could thus focus more of their attention on McNamee, as opposed to trying to discredit their clients' former teammates.

Prosecutors, however, can still use former Mets clubhouse attendant Kirk Radomski to support McNamee. Radomski is expected to testify that he was the source for performance enhancing drugs that McNamee used with baseball clients. Radomski has also said that he sent HGH to Clemens' house in Houston when McNamee went there to train him.

Pettitte, moreover, should still be able to testify as to his conversation with Clemens in which Clemens allegedly told Pettitte he used PEDs. But if Pettitte cannot discuss his relationship with McNamee, Clemens' legal team may be precluded from questioning Pettitte about the extent to which he used PEDs. In this respect, Judge Walton's denial would be an advantage for prosecution.

Pettitte testified before Congress that he used Human Growth Hormone (HGH) only twice -- for two days in 2002 to help recover from an elbow injury and for one day in 2004 to help recover from an arm injury -- which is once more than he admitted to the Mitchell commission. Based on conversations with members of Congress after Pettitte testified, it is clear they found him sincere and believed him not to have a dog in the fight. U.S. Rep. Elijah Cummings, for instance, lauded Pettitte. "Having a guy like Pettitte" as an independent witness, Cummings told SI.com in 2008, "that makes a difference." Cummings further said that he saw Pettitte as a "very religious" and moral man who "told us things [in his deposition] that we didn't even know," as opposed to just corroborating other peoples' accounts.

If Clemens' attorneys believe that Pettitte has understated the extent to which he used HGH, they would likely want to ask him about it. And if Pettitte testifies to more frequent usage of HGH than he admitted to members of Congress, his credibility would be damaged and the government's case against Clemens would suffer a potentially major setback. Judge Nelson's likely ruling, however, would preclude questions about the relationship between Pettitte and McNamee, thereby probably blocking such questions.

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