Sergeant John Young was gunned down during an attack at the Ingleside station in 1971. Seven men are charged in the case. Prosecutors say one of the men's colleagues will testify against them.
Prosecutors say all belonged to the Black Liberation Army.
But, a defense attorney says the men cannot get a fair trial because too much time has passed, resulting in lost or missing evidence.
Supporters for the defendants held a rally outside the hall of justice Monday.