When he was made assistant manager of a pool in Fairfax, Virginia, two years ago, Mateusz Fijalkowski spoke barely any English and did not know how to swim. In the United States from Poland on a summer program, Fijalkowski spent most of his time here hospitalized after nearly drowning in that pool. Now Fijalkowski, 23, is suing the police officers and lifeguard who pulled him out. Often police are sued for being too aggressive with mentally ill people; in this instance, they are accused of not doing enough to stop a man in the midst of a bipolar episode. Fijalkowski...