I suppose I have always been under the impression that if you were involved in a self-defense shooting you could reasonably expect to be tested for drugs and alcohol. Is that an incorrect impression? Would they still need to have specific cause to order you to undergo testing such as in your examples?
Let's say for the sake of discussion that your home is clean- you have used with friends outside the home.
If you are tested and come out positive, could you be charged under state law in CO? Would they need to elevate it to the federal level to bring charges?
I believe that they would have to prove that you were 'under the influence' at the time of the shooting. Just have drugs in your drug test I do not believe would count. I also think that they would need cause to do the drug test(AKA: on the night of the incident you tell the cop you were high on pot when someone broke inside). also, there is not too much protocol with that one(as in .08 alcohol is too drunk too drive, .02 is too much under alcohol influence to CCW, etc). Therefore, without the being under influence at 'time of incident' I don't think it matters. I don't believe they even test hardened criminals too often when they get a DUI for like if they are on cocaine etc as one example.
just my two cents