TMZ has learned ... Charlie Sheen and Brooke Mueller's custody settlement provides that neither is required to undergo drug testing ... something that is becoming increasingly troublesome.
As TMZ first reported ... Brooke was photographed last week holding what appeared to be a crack pipe. And there are other problematic images as well -- like the one recently in Hawaii, when Brooke walked up to a parked car in a seedy area with cash in hand.
HuffPost Lifestyle is a daily newsletter that will make you happier and healthier — one email at a time. Learn more