Is it legal to have sex with Justin Bieber?

In the USA there is something I think that is a little weird. They have 50 states and all 50 states are allowed to have their own laws on many areas, like abortion and gay marriage. That means that if you cannot get an abortion where you live you might be able to drive 30 minutes to the next state to get the abortion. A little weird right?
Anyways. One of the laws each state are allowed to set