Yale economics professor and former Mexican President Ernesto Zedillo has become a legal headache for the United States.

Zedillo has been accused of perpetrating the 1997 Acteal massacre when he was president by relatives of the victims. Plaintiffs are demanding $50 million in damages.

The infamous Acteal massacre was a political and religious assassination of 47 Maya Indian women and children in the hamlet of Acteal, Chiapas. Even after the alleged culprits spent 10 years in prison, it is not clear who ordered it or why it was carried out. It was a senseless act committed during Zedillo’s 1994-2000 administration.

The former president requested immunity, and Felipe Calderón’s administration has requested immunity for Zedillo in accordance with the Foreign Sovereign Immunities Act.

The U.S. Justice Department would have no problem granting Zedillo immunity. Zedillo is guilty of having been president of Mexico at the time of the massacre, but otherwise he was both a good friend of the U.S. and the first Mexican president to enforce democracy in his battered nation.

The real problem is that if he is granted immunity, the Foreign Sovereign Immunities Act could easily apply to all kinds of rogue African and Latin American dictators, opening the door to them seeking refuge in the U.S. Granting Zedillo immunity would be tantamount to inviting Fidel Castro and Hugo Chávez to seek American refuge. A final decision will come on Sept. 7.