UPDATE: The owner of the company in question has emailed me to tell me that he's taken down the bootleg t-shirts. I consider the matter closed at this point. Thanks for all your support and kind words, but please don't bug this guy anymore, he has done the right thing.
Looks like there's a t-shirt company (no links, I don't want to promote the bastard) that has copied my Republicans for Voldemort design and is making their own identical counterfeit t-shirts (selling 'em for two bucks more than we are, as well).
The owner doesn't seem to see a problem with this. Since I'm using the name of someone else's character on the shirt, he feels it's his right to copy my design and use it as well.
Thing is, we know that Warners and Scholastic folks know about our merch. They've bought dozens of shirts from us at a number of conventions, and told us that J.K. Rowling herself would most likely find it amusing. I don't know how much stock to put in that, and I'm not going to email the lady to ask her. I'm not one to look a gift horse in the mouth. That said, they seem to have left us alone to do our thing. Plus, I'm of the opinion that our shirt is genuine political speech and parody, and as such should be protected speech (I'm aware that current legal opinion does not always agree with me on this point).
This guy, though? Most of his shirts are blatant copies of IP from large, lawyer-infested companies. Hasbro, Nintendo, just about every movie studio in existence. Just straight-up knockoffs, no original thought or designs at all.
It's kind of an interesting situation. You've got a spectrum of legal grayness here, and one could say that if you're going to use someone else's trademarks in your design, even as a parody, you get what you deserve. In my mind, the difference is that my design is transformative. His is a xerox copy with no added value. Regardless, he's right. There's not much I can do about it.
But what he did was super-shitty. I asked nicely if he was interested in buying shirts from us, or licensing the design, and he pretty much told me to go to hell. I'm not a huge international conglomerate, here. I depend on my creative skills to put food on the table, and you shouldn't get between a hungry dog and his food dish.
I might not be able to take legal action myself, but I'm guessing that all those big-money companies would love to hear about this guy's operation.