Park Life on Clement Street in the Richmond District received the letter just before Christmas. Artist Jeff Koons created a giant shiny balloon dog, which was shown at Versailles and museums in New York.
The legal action raises an interesting question. Can you copyright an image of something that's seen and used in many different ways?
"Party clowns make balloon dogs for kids at parties. Do they have to stop making balloon dogs?" asked Park Life co-owner Derek Song.
Park Life has stopped selling the bookends, until they hear from the manufacturer, which says it will fight the cease-and-desist letter.