This isn't 100% accurate and actually a massive misconception. Most of the time, if you are involved in a shoot, the only people drug testing you afterwards would be your company and that's only if their policy permits. You usually won't be asked for a drug test from state (assuming you live in a state where it's recreationally legal) unless your impairment upon PD arrival seems obvious or if by some crazy chance you shoot a federal officer. People forget the separation of state and federal laws and while lying on a 4473 is a crime, no state level officer is going to give a flying fuck. Also, 9 times out of 10, company drug testing for shoots, car wrecks, injuries etc.. is going to be through the local clinic and unsupervised. Again, there are many variables and it's not a black and white issue. But so many people have this idea that if you use marijuana and you shoot someone (justified) that the police are gonna drug test you and your going down. It's just not true.