To quote Gregory House, "Everybody Lies" and teenagers are no exception to the rule. He seems to just be a more lenient in his parenting style. Now, this doesn't have to be a bad thing, but from what I have seen this tends to lead there being "the good parent" who believes everything and does spoil, and the "bad parent" who knows when lies are being told, disciplines, etc, which can make things uncomfortable.

I think he just needs to make a compromise with you so that kind of thing doesn't happen.