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?