President Donald Trump announced Monday that he is federalizing the Washington, D.C., Metropolitan Police Department to address a “public safety emergency,” a move that will give him complete law enforcement control over the district.

Trump has the authority to temporarily take control of the local police. For the president to mount a full federal takeover of the city, however, Congress would first need to repeal the 1973 Home Rule Act, which granted D.C. a level of self-governance.