The Mexican government might sue the U.S. Army reservist who detained a group of illegal aliens in Arizona last month. Local officials decided that he did not commit a crime. (Backstory here, results of a poll on his actions here.)

Mexico is reportedly working with a "human rights group" in Los Angeles on the matter. "Mexico may sue reservist in migrant detention" has a few more details:

The lawsuit could argue that reserve Sgt. Patrick Haab engaged in assault or illegal detention of the immigrants or caused them mental anguish, [Geronimo Gutierrez, the Mexican deputy foreign secretary for North America] said.

I can think of at least three usual suspects that Mexico might be working with, and I'll update this post if I find out which it is.