Legal Question in Family Law in Montana

Be aware that accusing the other parent of using drugs is a very common tactic to gain the upper hand in a parenting dispute. It's likely that the court will receive your claim with some skepticism. The age of the child witness is important to the credibility of a drug-use claim. Old enough to know what the parent is doing, or young enough to inaccurately describe what s/he saw?

If the child is old enough, s/he can talk with the judge in-chambers. Only the judge's court reporter attends (and perhaps the judge's clerk) -- no parents or lawyers, although the child's guardian ad litem might be permitted. The child can talk with the judge about the "when, where, and what" of dad's drug use, whether he's alone or has friends using with him, who those people are if the child knows their names, and if your son does not want to be with dad during this time, he could also talk about that. The conversation is "on the record" but is sealed so the parents and their attorneys do not know what the child talked about.

Request a hair follicle test, and expect the other parent to demand that you also be tested. Request that dad attend drug and alcohol counseling, and expect him to demand it of you, too. If dad claims it's medical marijuana, you can request medical records to verify his diagnosis.