The Supreme Court on Thursday put an extra burden on crime labs, declaring that a man accused of drunken driving has the right to demand that a lab technician testify in person about a blood test that showed he was impaired. The 5-4 decision was the latest to extend the reach of a defendant's constitutional right "to be confronted with the witnesses against him." And once again, the outcome was driven by an unusual coalition of conservative and liberal justices. Two years ago, the court said a crime lab technician was a witness for the prosecution and, therefore, must be...