Trouble implies legal difficulties, as in criminal charges. The fact is that there are no laws anywhere, in any state of the US that precludes anyone dating (the activity of going out regularly with somebody as a social or romantic partner). However, to do so with someone who is below the age of eighteen (18) is potentially courting disaster. It is a precarious position one can find himself in by dating a minor. He becomes vulnerable to accusations of a criminal nature, and such accusations are difficult to impossible to defend against. So, it really depends on several things:
- The age of both parties -- vis a vis whether one or both are minors, more specifically if the female is a minor as males are more often accused and charged criminally whether they are minors or not.
- The laws specific to your state - some states such as California (but not exclusively) set the age of consent at 18. Federally it is 16, but (most importantly) even the age of consent does not preclude prosecution, it only provides some minimal defense in the event of prosecution.
- Only one state, to my knowledge, has a "Romeo & Juliet" law that precludes prosecution for couples no more than four years separated in age. That is currently Michigan. This however may be changing, and more states may have adopted this policy.
- The age and maturity of the two. Some people are more mature than others and are prepared to handle the emotional roller coaster of dating. More often, younger people are not, thus making the chronological age more important from a legal perspective.
- The level of vindictive behavior of the parents of minors involved in the relationship. Neither of the two in the relationship need make an accusation to law enforcement for charges to be brought. Neither is it necessary for either to cooperate with law enforcement in any investigation. Many situations where charges have been brought, it is the parents or other adults in the lives of the couple who bring the charges, and once the ball starts rolling, very little will stop it.
So, go cautiously. It is a brave new world we live in, and a three year difference will get you a life sentence (perhaps literally and figuratively).