NEW YORK POLICE may not choose which photographs from a livery cab camera to preserve for a robbery prosecution, a judge in Brooklyn has ruled, warning that all pictures taken in the course of an incident must be saved for trial.

Justice Gustin L. Reichbach last month sentenced Rodney Cannon to a 3- to 6-year prison term after his conviction Feb. 28 in Supreme Court, Kings County on a charge of third-degree robbery. But the judge said he was issuing a post-trial written opinion to put the Police Department and District Attorney’s Office “on notice that [the policy of not saving all cab photos] must change . . . .”