Many police departments across the state of New York lack the technology and resources to maintain detailed records of their law-enforcement practices, according to a two-year study by the New York Civil Liberties Union.

The civil rights group, an affiliate of the American Civil Liberties Union, filed Freedom-of-Information requests to 23 New York police departments about stops, complaints of misconduct, use of force, surveillance, and racial profiling and found it difficult to get the data requested in most cases. Eventually,...