Sure. His criminal conduct, if uncovered, can alter things for you and the two year old. May be he is not a criminal. If he uses, then his chances of getting what he wants in the visitation battle are diminished.
It could if someone with an interst in your child (i.e. CPS) finds out and wants to do something about it. He needs to pass the drug test and then he won't have much to worry about. Get a good lawyer - 14 and 16 year old kids rarely need their visitation with dad to be "supervised." This is probably more driven by her jealousy of you and your new child than anything about safety. Let's be honest - no one ever got high on marijuana and beat their children. It is illegal, however, and that matters - so just tell him to clean up and pass the drug test. Your problems shouldn't last too long after that.
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