How individual police forces treat those that they suspect of being illegal immigrants varies greatly from one city to the next in the U.S. In Albuquerque, New Mexico, the police department has a policy that states clearly, “Officers shall not stop, question, detain or arrest any person on the ground that they may be undocumented and deportable foreign nationals.” But this is unusual. Local police departments across the U.S. have become increasingly involved in enforcing federal immigration laws since the mid-1990s.