Military corruption has prevented this in the past.
Mexico is currently in the process of undergoing a change in their military structure that may have many effects on the way their ongoing war against the drug cartels plays out. As things stand now, military personnel, regardless of whatever crime they happen to commit, get tried under a military court on the grounds of breaching military discipline. Now, a judge's ruling has stated that this sort of system goes against the constitution of the country and that it needs to be changed.
