The most basic responsibility of an officer of the law is to obey the law. The police and federal agents have enormous powers. They can arrest people, forcibly enter their homes and commit violence in the government's name. If they violate the rules for using those powers, they can become abusers of the citizens they are entrusted to protect. The Department of Homeland Security under President Trump has followed this dark path. Too often over the past year, its behavior has been lawless.