Is it art or a crime?

[Professor S]

The answer is quite simple:

If the art is sanctioned by the rightful owner of the property that it appears on, its legal.

If not, its still art, but it is a crime.

As for the law banning youth from owning spray paint and markers under age 21, that is an abuse of power and the law, but its not against the 1st amendment.

Just because you own paint and markers doesn't mean that you are going to create illegal graffiti with them. They are tool that can be used for many things besides illegal activities and anyone has the right to own them and have them on their person.