Attorney General Martha Coakley is preparing to argue before the US Supreme Court in a case to decide whether prosecutors can use crime lab reports as evidence without having the forensic analyst who prepared them testify.
The reliability of crime labs has been questioned in recent years.
Monday's case involves Luis Melendez-Diaz, convicted of trafficking in cocaine partly on the basis of a crime lab analysis that confirmed cocaine was in plastic bags found in the car in which he was riding.
Melendez-Diaz argued that he should be allowed to question the person who prepared it about testing methods, how the evidence was preserved and other issues.
A brief supporting Melendez-Diaz points to problems at the Massachusetts state lab.
Massachusetts AG Coakley argued that requiring lab technicians to testify in support of their findings would be prohibitively expense and hinder prosecution of low-level drug prosecutions. "Misdemeanor drug prosecutions would essentially grind to a halt," she is quoted saying in USA Today.