This bill prohibits the District of Columbia (DC) from limiting its cooperation with federal immigration enforcement activities, except for certain instances involving witnesses and victims of crime. Specifically, the bill bars DC from adopting a law, policy, or practice prohibiting DC governmental entities from sending, receiving, maintaining, or exchanging information regarding the citizenship or immigration status of any individual with a federal, state, or local government entity. Further, DC may not adopt a law, policy, or practice of not complying with lawful requests from the Department of Homeland Security (DHS) to comply with a detainer for, or notify about the release of, an individual from custody. (A detainer is a formal request from DHS that a state or locality hold an individual in custody for up to 48 hours after the individual would otherwise be released so that DHS may facilitate the individual's removal.) The bill provides exceptions allowing DC to adopt policies of not sharing information or complying with a detainer request regarding an individual who comes forward as a victim or a witness of a crime.