This site should answer some of your questions:
http://www.tortoise.org/general/4inch.htmlThe FDA regulates this. If the person is found to be commercially selling turtles under 4" in length, the turtles would be destroyed. If they are not "commercial" but just his "hobby" or some other way for him to get out of it, he might be fined a few pennies for animal neglect or something. I'm afraid the laws really don't help the turtles. The FDA probably wouldn't bother with the turtle you've bought even if you told them. They've got more important things to do. Then again, well, you know the government sometimes prefers to go after the little guys and, well,...