OTOH, if you lied to me and I found out you were busted for a tiny amount of weed, I'm going to burn your application. Not because of the arrest - again, I don't even care about that - but because you've lied to me. At that point I'm not going to trust anything else you tell me. Are you also going to cover your mistakes at work and hope no one notices?
Every company is different, so I'm only speaking for myself and not the industry as a whole. But I would infinitely prefer that a candidate tell me this stuff up front than to try and hide it from me. And frankly, if you got arrested for some very cool reason ("I was part of a protest against a white supremacist march!"), it could quite possibly tip the hiring decision in your favor!