teenage discipline

[MommyBj]

I have a guy friend who's 16 year old son has recently moved in with him (in November). Before, the kid lived in Hawii with his mom and was involved in gangs. He seems to be headed down the same track and the father is very concerned. He doesn't know what to do for him. The son stays out all night, skips school, hangs out with drug dealers and (believe me here) trashy looking women. What can he do? He has let the son know that he needs to help with cleaning the house and he needs to come home at a decent time at night, but the son doesn't do it. If the father confronts him, how should it be done? What kind of circumstances should be set and how can he enforce them when the son can just walk out of the house?