DNA could spell trouble for Clemens

Roger Clemens testified under oath before Congress last February that he did not use steroids or performance-enhancing drugs. AP

Reports surfaced on Monday that Roger Clemens' former personal trainer, Brian McNamee, gave samples of his DNA to federal investigators who are trying to determine whether the former pitcher committed perjury before Congress when he testified last February that he had never been injected with human growth hormone or steroids. The major point to be drawn from that news is that McNamee's evidence is stronger than it initially appeared, and that raises the probability that the evidence would be deemed admissible and persuasive in a trial.

The basic rule for admissibility is that if the danger of unfair prejudice posed by a piece of evidence would outweigh its probative value, then a judge should deem the evidence inadmissible. Given that there is readable DNA on the syringes, needles and gauze pads preserved by McNamee (and which he turned over to federal prosecutors in January), those pieces of evidence would appear to offer more certain probative value. Although it may seem peculiar, even bizarre, that McNamee would keep those items for six years, his decision to do so may ultimately be vindicated in this case.

However, it's still not clear that the DNA evidence actually links Clemens to the items handed over by McNamee, and absent that connection Clemens is poised to escape criminal prosecution and civil liability. If it's true, as Clemens' lawyer, Rusty Hardin, seems to be implying, that his client would be willing to provide federal authorities with a DNA sample -- he told The Times, "As I have said from the beginning, we are willing to cooperate with any aspect of the government's investigation" -- then investigators should be able to determine whether Clemens' DNA matches that on the syringes. A match would increase the chances that the government seeks a grand jury indictment against Clemens on perjury and obstruction charges. It would also stymie, if not outright preclude, Clemens from succeeding on his already quixotic defamation lawsuit against McNamee.

So another potentially interesting dimension to this story is whether Clemens would object to offering a DNA sample. Hardin implies that Clemens would volunteer his DNA, but what happens if Clemens changes his mind? Prosecutors could seek a court order directing that he submit to the taking of a biological sample pursuant to a search warrant. Probable cause would be required for the issuance of such a warrant. Clemens' DNA would need not be drawn in an invasive method, as a small amount of saliva would suffice, meaning a blood sample would not be necessary. Clemens could nonetheless refuse to provide a DNA sample on privacy grounds, though his refusal to offer a biological sample could be admissible at trial as circumstantial evidence.

Even if there is a match between Clemens' DNA and that found on McNamee's materials, Clemens' legal team would likely claim that McNamee tampered with the items to produce a match, or that the evidence is unreliable on other grounds (e.g., it's too old to be reliable; the items were mishandled or have some other defect, etc.). But a DNA match would be a big blow to Clemens. Bottom line: This latest news, if accurately reported, is not good for Clemens.

Michael McCann is a visiting law professor at Boston College Law School, a law professor at Vermont Law School and the distinguished visiting Hall of Fame Professor of Law at Mississippi College School of Law.