NEW YORK (WABC) -- New York City's Department of Investigation on Tuesday released a report on its review of the NYPD's compliance with the court-mandated rules governing the investigation of political activity.While the NYPD inspector general found the department was able to justify every investigation into Muslim groups launched by its Intelligence Bureau, the study found the NYPD routinely broke its own rules regulating its investigations over the last five years.The Intelligence Bureau is supposed to get permission to continue probes of political activity within specified time limits, but the report found the department doesn't bother more than half the time, resulting in "investigations of political activity that continued without the requisite authorization."The Intelligence Bureau also frequently failed to spell out the role of undercover officers and confidential sources used to infiltrate and monitor these groups."This investigation demonstrates a failure by NYPD to follow rules governing the timing and authorizations of surveillance of political activity " DOI Commissioner Mark Peters said. "While we found no evidence of improper motives, these rules are important to protect the rights of all New Yorkers and must be rigorously followed. We will continue our oversight to ensure compliance going forward."NYPD Inspector General Philip Eure, whose position was created in 2014 by the City Council amid stop-and-frisk criticisms, was able for the first time to review a random sample of internal documents generated in NYPD Intelligence Bureau cases closed between 2010 and 2015.DOI found investigations in 25 percent of the sampled cases continued for more than a month past when the bureau should have obtained renewed authorization.The NYPD's Patrol Guide also specifies that the department must spell out, in detail, facts justifying opening a probe and the specific role of undercover cops or confidential informants."Without this information, a reviewer cannot determine whether the use of an undercover is necessary," the report stated.DOI found the Intelligence Bureau included no factual information detailing why it was using undercovers and the roles they would play in the sampled investigations.NYPD officials responded by saying that the inspector general's complaints only involved "technical administrative issues" and that he never questioned the validity of the investigations he reviewed. They also said they have implemented an electronic tracking system for cases that will notify them when authorization for surveillance has expired. CLICK HERE to read the full report.