I agree with the others. He is teaching your younger one the same behaviors, so if you don't get him straightened out by not bailing him out and not allowing him to use drugs in your home, you will be dealing with two of them soon. Ask yourself if you can handle two of them doing this to you??
If he gets arrested, don't bail him out. If he's drugging in your house, call the cops. Do it once, and he will believe you!!! Then tell him to "get used to it"