https://www.justice.gov/jm/1-16000-department-justice-policy-use-force#1-16.200

"Deadly force may not be used solely to prevent the escape of a fleeing suspect.

Firearms may not be discharged solely to disable moving vehicles. Specifically, firearms may not be discharged at a moving vehicle unless: (1) a person in the vehicle is threatening the officer or another person with deadly force by means other than the vehicle; or (2) the vehicle is operated in a manner that threatens to cause death or serious physical injury to the officer or others, and no other objectively reasonable means of defense appear to exist, which includes moving out of the path of the vehicle. Firearms may not be discharged from a moving vehicle except in exigent circumstances. In these situations, an officer must have an articulable reason for this use of deadly force."