Implications of Positive DNA Test Result for Roger Clemens

I have a new column on SI.com regarding an apparent match in the DNA of Roger Clemens and that found on materials containing steroids. Here's an excerpt:

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.

For the rest, click here.