[bunderbunder]

They do operate legal entity in the US. At the very least, there were all those funds the Feds seized last year.

The U.S. doesn't necessarily have to enforce its laws overseas to go after Mt. Gox. Japan has its own consumer protection laws, and presumably they have something to say about how Mt. Gox has been operating, too. So filing suit in a Japanese court is also a perfectly legitimate option.