The overall number of arrests, stops, moving violations and criminal summonses issued in New York City has fallen substantially over the past four years, according to a study released on Friday.

The decrease in those law enforcement actions, to 1.82 million in 2014 from a peak of 2.63 million in 2011, was driven primarily by a steep decline in the use of the tactic known as stop-and-frisk, according to the study, which was conducted by the Misdemeanor Justice Project at the John Jay College of Criminal Justice. The routine use of the tactic, which was heralded as a key anti-crime strategy, is recorded at far lower levels today, after a federal court found in 2013 that it was used excessively and unconstitutionally.

The drop indicates progress toward a goal articulated in March by Police Commissioner William J. Bratton, to decrease annual law enforcement actions by one million by the end of 2015 compared with recent years. He has called it a “peace dividend,” and says officers are encouraged to use greater discretion in exercising their authority and to improve relations between the police and the communities they serve.

Encounters between the police and the public began to decline under Mayor Michael R. Bloomberg and Police Commissioner Raymond W. Kelly, and has continued under Mayor Bill de Blasio and Mr. Bratton. Mr. Kelly was a critic of reducing stop-and-frisk use, and predicted that it would lead to a rise in crime.