Divorce Support Forums: visitation enforcment

I have a 16 year old son who does not get along well with his dad. He now states that he never wants to go to his dad's house for visits, since he is 16 he feels he can make that decision. As far as what I know, he is supposed to go until he is 18. My question lies in the enforcement issue. My ex thinks I should force him to come over during his week and that I should not be allowed to pick my son up from his house during visitation for any reason. My son is taller and heavier than me -- how am I supposed to get him over there when he feels it is his right to not comply with visitation? My ex has threatened to take me back to court (again)on contempt charges if I do not make the visitation happen every other week for the next 2 years. Does anyone know how I can protect myself if a contempt charge is brought against me? I think my son should spend time with his dad, but he is being stubborn. Any ideas??