The fourth installment of the Blue-on-Blue Crossfire series examines fire discipline as firing only when required and holding fire without a positively identified threat or a safe line of fire that would not endanger bystanders.

It cites the July 4, 2022, parade shooting in Highland Park, Illinois, civilian rooftop security in Koreatown during the 1992 Rodney King riots, and an officer at Robb Elementary who did not fire on a person in black clothing matching a dispatched suspect description.

Earlier parts addressed sympathetic fire and plunging fire. A later installment will use a hostage rescue drill.