That official, John J. Miller, the Police Department’s deputy commissioner for intelligence and counterterrorism, said the office of the inspector general, Philip K. Eure, had given the Police Department “very high marks” on issues involving “whether we were looking at the right people for the right reasons within the bounds” of privacy guidelines.

Members of Mr. Eure’s staff, as part of their inquiry, analyzed a set of cases closed from 2010 to 2015 — but opened as early as 2004 — to test for compliance with a set of safeguards known as the Handschu Guidelines. Those guidelines were created in response to a 1971 class-action lawsuit and are meant to protect political and religious activities from overreaching police surveillance.

From a broad perspective, the inspector general’s office found, the Police Department was always able to explain its rationale for new cases and always met the “informational threshold” required to open them. The report said that there was no evidence of “improper motives” on the department’s part in those cases.

The report said, however, that the failures that had been uncovered demonstrated “the need for ongoing oversight” of the department, and it included 11 new recommendations. Mr. Eure said that adopting the recommendations would “give the public greater confidence” in how the police operate.

In January, Mayor Bill de Blasio, a Democrat, agreed to appoint a civilian to monitor the department’s counterterrorism activities as part of a settlement of two lawsuits claiming Handschu guidelines had been violated. That settlement has not yet been approved by a federal judge, according to the New York Civil Liberties Union, which represents plaintiffs in one of the suits.