IN THE FIRST OPINION FROM ITS newest justice, the U.S. Supreme Court has given criminal defendants something most Americans assumed they already possessed: the right to offer evidence that somebody else committed the crime. But that's only part of the significance of this week's unanimous ruling setting aside a murder conviction of a South Carolina man. The decision, written by Samuel A. Alito Jr., also puts police and prosecutors on notice that the "magic bullet" of evidence -- DNA -- can misfire if physical evidence and test results are handled carelessly.
Law enforcement officials should have learned that lesson after the 1995 acquittal of O.J. Simpson on charges that he murdered his wife and her friend. Jurors in the trial cited defense claims that sloppy handling undermined the credibility of DNA evidence. This week's Supreme Court decision also involved DNA evidence, which (along with a palm print and fibers) led prosecutors to charge Bobby Lee Holmes with the 1989 rape and murder of an 86-year-old woman. Relying on a state rule, the trial judge ruled that this evidence was so strong that Holmes' lawyer couldn't call witnesses who would support the theory that another man committed the crime.
Most Americans would be shocked by the suggestion that someone on trial for his life couldn't offer evidence that someone else was guilty. So were both liberal and conservative members of the Supreme Court, led by Alito, a former federal prosecutor.