Rodrigo Duterte, sworn in today as president of the Philippines, may face legal obstacles to his campaign promise of killing the country’s one million illegal drug users.

Duterte, nicknamed “the Punisher” by various media outlets, has called for the execution of drug traders and users throughout his political career. In an election rally in May, he issued a stark warning: “All of you who are into drugs, you sons of bitches, I will really kill you. I have no patience, I have no middle ground. Either you kill me or I will kill you”.