-Mugz is correct, there is no drug testing questions. However, there is more to this post....I think. The OP is pretty damn vague.
-This is a cannabis question, so yes, it would belong in cannabis discussion.
-OP, we have no idea. Different law enforcement agencies have different procedures. Not to mention that different localities, cities, counties, states, countries and individual police officers do things differently.
In the end, this is something you need to discuss with your lawyer. None of us are lawyers, and even if we were lawyers, none of us are your lawyer. I'm going to close this because it is not within the scope of this forum and even if it was, the question is too vague to be answered.
PM me if you have any questions, OP.