DNA evidence will likely play a role in Clemens' perjury case
Tests have linked Roger Clemens' DNA to blood in Brian McNamee's syringes
Clemens' counsel will have numerous fronts on which to rebuke the evidence
The evidence raises the likelihood that Clemens will be indicted by a grand jury
According to The Washington Post, preliminary DNA tests of syringes provided by Roger Clemens' former personal trainer, Brian McNamee, reveal a match with Clemens' blood. Assuming the results are corroborated by additional testing, the evidence raises the likelihood that Clemens will be indicted by a grand jury and brought to trial on perjury charges in connection with an investigation into whether Clemens lied under oath to Congress last year when he denied using steroids or HGH.
One immediate consideration is whether the DNA evidence would be admissible in a trial. The short answer is yes, it would very likely be admissible.
Generally, evidence is admissible if its probative value, which refers to information bearing on the defendant's culpability, outweighs its potential to unfairly prejudice the defendant. In a perjury trial of Clemens, a court would need to assess if Clemens knowingly lied under oath about his alleged use of steroids. The presence of Clemens' DNA on McNamee's syringes would suggest that Clemens lied, meaning the evidence would have high probative value. In contrast, the evidence's potential to unfairly prejudice Clemens would be muted by the fact that any evidentiary defects could be raised during cross-examination.
Although the DNA evidence -- needles that McNamee said he used to inject Clemens and gauze used to wipe blood off Clemens after a shot -- would likely be deemed admissible, Clemens' counsel would have numerous fronts on which to rebuke it during cross-examination.
First, Clemens' counsel could argue that the evidence results from McNamee's tampering, such as McNamee removing a trace of Clemens' blood from a syringe that had been used to inject Clemens with a benign substance and placing it on a needle containing a steroid, thus triggering a fallacious match. Given that McNamee worked closely with syringes and related materials, he likely had the know-how to deftly manipulate them in ways unknown to the average person. Plus, given McNamee's proffer agreement with the government (which required McNamee to truthfully reveal information to prosecutors in exchange for any disclosures not being used against him), he may have been motivated to implicate Clemens, thus providing a rationale for tampering.
Second, Clemens' counsel could maintain that even if McNamee did not deliberately tamper with the evidence, the circumstances in which he preserved the evidence are dubious. (McNamee apparently preserved the evidence in a box in his basement, and kept the needles in a beer can that he says was removed from the trash at Clemens' New York apartment in 2001.) Clemens' counsel would likely compare the preservation qualities of McNamee's basement with those of a reputable laboratory, and it seems likely that such a comparison would reflect poorly on the evidence.
Third, even if the DNA match derives from a pristine sample, Clemens' counsel could argue that the pitcher never knew that McNamee was injecting him with steroids. Like Barry Bonds has maintained in regards to his former personal trainer, Greg Anderson, Clemens could profess ignorance as to any nefarious contents in the injections. While such an argument may seem farfetched, if Clemens' counsel could establish the potency of non-steroid injections, such as those containing vitamin B-12, then Clemens might persuade a jury that he was genuinely misled. If so, he might instill in the jury the requisite "reasonable doubt" to find him not-guilty.
SI.com legal analyst Michael McCann is a law professor at Vermont Law School and the distinguished visiting Hall of Fame Professor of Law at Mississippi College School of Law. He is a former chair of the Association of American Law Schools' Section on Sports and the Law.