 This "defense of life" rule replaced the "fleeing felon rule".The 1985 Supreme Court decision, "Tennessee v. Garner" ruled that police may only use deadly force to prevent escape "when" the officer has probable cause to believe that the suspect poses a significant threat of death or serious physical injury to the officer or others.Since the NYPD instituted new policies on use of force, many other law enforcement agencies have followed suit, establishing written policy that set guidelines as to when use of force is appropriate.