State Attorneys General Empowerment Act of 2020 This bill expands civil enforcement against state and local law enforcement agencies that engage in patterns or practices of conduct that violate constitutional or federal statutory rights. Among other things, the bill authorizes states to bring pattern-or-practice cases, gives administrative subpoena power to states (and to the Department of Justice) in pattern-or-practice investigations, and authorizes grants to help states conduct pattern-or-practice investigations.