Bangladesh, Sept. 1 -- Mexicos long-troubled justice system has once again come under scrutiny after a series of high-profile expulsions of alleged cartel members to the United States highlighted how powerful criminal figures have manipulated legal protections to delay prosecution and avoid extradition. The central focus of the controversy is the “amparo,” a constitutional safeguard originally intended to protect ordinary citizens from state abuse, but which has increasingly become a tool of choice for the countrys most dangerous criminals.

Earlier this month, Mexican authorities placed 26 suspected cartel operatives on a plane bound for the US, where they face indictments ranging from drug trafficking and money laundering to...