ikinman

Based on what you said, it's all pretty simple - you're right and they're wrong. The creator of a rendering (for now) owns the copyright unless you have signed away that right. You don't even need to have 'I own the copyright' in your contract. You just need not to put 'You own the copyright' in your contract.

That all being said, the situation is also pretty simple. They're violating the contract (though they may not be aware of how copyright law works - most aren't), and that's that. It's the same as if they refuse to pay you your entire fee. So what are you going to do about it? Well, in most cases it rarely pays to do anything about it. If your client is making a bunch of money off of your copyright, say by selling copies of your work on posters and the like, than a legal approach may be warranted. But in most cases it wont pay, and you'll lose the client. Typically a letter informing them of the situation is warranted, and because in many if not most cases people are generally decent and civil folk, that often will do the trick.

If they refuse, and you want to keep them as a client, then you should rethink your next contract. Let them know verbally the copyright situation, not just in your contract (which too many clients don't read anyway.) And raise your fees, and tell them why. If they are showing your work as their own, then presumably they like it enough to want more, so that gives you some leverage. Just don't sign away your copyright in the next proposal, unless you get specific extra bucks for it.

And if this sort of thing happens a lot, then consider registering the copyright on your works. It doesn't protect you any more, but it gives you the option of winning a much larger settlement in a court case, which means that a lawyer would actually take on your case. You can't get much out of a legal settlement for an unregistered copyright, so lawyers won't often take up that case.

But unless the stakes are high, legal options are almost never worth it. It comes down to how much you want to piss them off. There are a million clever and non-legal ways to do that, but you need to know your client and how badly you want their fees. We are in a service industry and it always comes down to how much we are willing to do for money.

-Ian