An independent police monitor found the New York Police Department violated surveillance laws, particularly when spying on Muslim groups. The report found NYPD’s intelligence division often continued surveillance after court permission for it expired.

As far back as 2004, the NYPD failed to get permission to continue investigations of Muslims groups, the New York Inspector General said. For its investigation, the IG used a sample of all cases closed between 2010 and 2015, some of which go back to 2004.

In 25 percent of the cases, surveillance investigations continue for more than a month past the when the bureau should have obtained renewed authorization.

The report, released on Tuesday, found that more than 95 percent of the people under investigation in the cases were “associated with Muslims and/or engaged in political activity that those individuals associated with Islam.”

The findings were "more evidence that the NYPD's surveillance of American Muslims was highly irregular, operated in a black box and violated even the weaker rules that existed before our proposed settlement," Donna Lieberman, executive director of the New York Civil Liberties Union, told AP.

The report comes eight months after the city agreed to settle two federal lawsuits with Islamic groups which argued the NYPD routinely violated their civil rights by conducting unwarranted surveillance of Muslims. As part of the settlement Mayor Bill de Blasio agreed to a committee with some civilian oversight of the NYPD’s Intelligence Bureau.

NYPD recording peaceful #PeoplesMonday, likely in violation of Handschu Decree, and thus constitution. pic.twitter.com/WWPX9nvZo5 — Keegan Stephan (@KeeganNYC) August 16, 2016

The suits were filed in response to reports by AP that revealed the NYPD infiltrated Muslim students group, put informants in mosques, and spied on Muslims as part of broad effort to prevent terrorist attacks.

While Inspector General Philip Eure said he “found no evidence of improper motives” by the NYPD, the report did find that in all the cases reviewed the NYPD failed to spell out the role of undercover officers and confidential informants or explain why they were necessary. Police officers included “no factual information,” instead using the same boilerplate language – including the same typos in every application.

"These failures cannot be dismissed or minimized as paperwork or administrative errors," said the report, as quoted by AP. "The very reason these rules were established was to mandate rigorous internal controls to ensure that investigations of political activity – which allow NYPD to intrude into the public and private aspects of people's lives - were limited in time and scope and to ensure that constitutional rights were not threatened."

When it comes to surveillance the NYPD’s own patrol guide handbook includes limits under the court-ordered Handschu Decree. The decree was put in response to NYPD illegal surveillance of war protesters in the 1960s and 1970s. It bans investigations based on race, religion or ethnicity and requires the use of the least intrusive investigative techniques possible. Those guidelines were modified in 2002, after the September 11, 2001 attacks, to allow the department’s Intelligence Bureau to deploy investigative tools when there is information indicating the possibility of unlawful conduct, including long-term surveillance and undercover operations.

Civilian to monitor NYPD spying in settlement over covert surveillance of Muslimshttps://t.co/yflAshaZu1pic.twitter.com/qpT08jtVCb — RT America (@RT_America) January 8, 2016

NYPD officials said the criticisms in the report were more technical than substantive, and that the department had introduced a new electronic tracking system that will notify them when surveillance authorization has expired.

"We believe we've adhered to the spirit and the letter of the law in each instance," the NYPD's top attorney, Lawrence Byrne, said at a news conference. "We don't break the law to enforce the law."