In New Jersey can a cop arrest you for underage drinking if he doesnt see you doing it?

Question

Say for instace say he takes you to the hospital and they check your blood alcohol level.

Answer 1

There is no requirement for him to actually see you drinking, he only needs to prove you were. If the evidence leads him to believe you were drinking, you can be arrested.

Answer 2

Yes.  You can be arrested for anything, as long as the officer has probable cause.  

Answer 3

well yea probably