The FBI said Thursday that it had discontinued the use of bullet-lead matching, a forensic technique used for at least 25 years that had been heavily criticized as inaccurate and misleading.
The bureau suspended its use in 2004 after a report by the National Research Council found the technique could be "seriously misleading" and "objectionable."
The council's finding called into question FBI testimony in hundreds of cases involving murder and other serious crimes.
"It's a victory for good sense and good science over the kind of nonsense the FBI was representing in court," said William C. Thompson, a professor of law and criminology at UC Irvine.
The FBI said it would alert about 300 courts and prosecutors that since 1996 had received bullet-lead laboratory reports indicating positive results.