Here's the logic behind that thought: unlike typical artwork which is executed wholly with materials owned by the artist, the act of tagging or 'bombing' relies on the illegality of the act - the artist usurps the wall or building or sign. It also relies on it being visible to as many people as possible. Frankly, you could argue it isn't really graffiti art if it isn't done on highly visible property that doesn't belong to the artist - it's nature, it's objective is to challenge the idea of art as private property. Hence, it belongs to everyone who sees it.
This makes any work executed by said tagger public property which isn't in its entirety the property or copyright material of the person executing it - the public is part of the process, and is as much a creator as the 'wrist' executing it. We the public are like a group of performance artists - we make it possible for the 'art' to exist - without our contribution, it isn't art, and the wrist isn't an artist. Once he/she makes their activity 'public', it belongs to us as much as it does to them.
I'm no lawyer, but my understanding is if one seeks the protection of the courts, one has to enter with 'clean hands.' Can a person who has committed an illegal act - tagging - expect copyright protection for the output of that activity? I don't know. I don't think they should. But if they do, shouldn't we be prepared to fight for our rights as co- creators too?
Why is this important? Well, the marginally successful taggers have sold their art to companies like Nike. I think its about time the public enjoys their fair share of the pie.
