(CNN) New York Attorney General Letitia James is suing the New York City Police Department and its leadership over its "excessive, brutal and unlawful" handling of George Floyd protests, James said in a news release.
James also wants to install an external monitor to oversee the department's policing tactics.
The suit, filed Thursday in Manhattan federal court, comes after a monthslong investigation into the NYPD's actions during protests from May through December over the killing of Floyd while he was in police custody in Minneapolis on May 25.
The investigation found that officers allegedly used "indiscriminate, unjustified, and repeated use of batons, pepper spray, bicycles and a crowd control tactic known as 'kettling' against peaceful protestors," the release said.
"There is no question that the NYPD engaged in a pattern of excessive, brutal, and unlawful force against peaceful protesters," said James.
"Over the past few months, the NYPD has repeatedly and blatantly violated the rights of New Yorkers, inflicting significant physical and psychological harm and leading to great distrust in law enforcement."
The suit names the NYPD, the city, Mayor Bill de Blasio, NYPD Commissioner Dermot Shea and NYPD Chief of Department Terence Monahan as failing to address a "longstanding pattern of abuse" by not properly training, supervising and disciplining officers to prevent and address misconduct, the release said.
NYPD Deputy Commissioner John Miller said Thursday that the department "welcomes reform" and but reiterated that "adding another layer of oversight does not speed up the process of reform."
"Our reform does not start at the George Floyd protests," he told reporters. "We've been in a state of reform that goes back many years. The suit as filed doesn't seem to meet the standard for a federal monitor and it doesn't seem to illustrate a pattern and practice which is required under the law."
In a statement to CNN, de Blasio said he met with James on Wednesday and the two share a common goal "to drive major police reforms."
"I couldn't agree more that there are pressing reforms that must -- and will -- be made this year," de Blasio said, adding that those include major discipline reforms and recommendations from a city Department of Investigation report.
"That work is critical and is happening right now. A court process and the added bureaucracy of a federal monitor will not speed up this work. There is no time to waste and we will continue to press forward."
Patrick Lynch, president of New York City's Police Benevolent Association, said in a statement that what the city witnessed in June was "a failure of New York City's leadership."
"They (city leadership) sent cops out to police unprecedented protests and violent riots with no plan, no strategy and no support," Lynch said. "They should be forced to answer for the resulting chaos, instead of pointing fingers at cops on the streets and ignoring the criminals who attacked us with bricks and firebombs."
The union submitted testimony as part of James' investigation, including testimonials from injured officers.
The complaint filed Thursday includes dozens of examples of what the attorney general called blatant use of excessive force and other misconduct by officers. James said that since May her office had received more than 1,300 complaints, conducted a three-day public hearing and collected more than 300 written statements.
A hospital employee on the front lines of the fight against Covid-19 at a news conference announcing the suit Thursday described how he was allegedly attacked by NYPD officers on his way home from a shift.
Rayne Valentine, who works at Kings County Hospital in Brooklyn, said he was walking to a subway station after his shift and saw at least six NYPD officers pursuing and then using physical force against another man during a protest. Valentine said he began to record what was happening on his cell phone.
The hospital worker said an officer told him to get back and that he complied, but the officer still charged at him. The lawsuit alleges multiple NYPD officers hit and kicked Valentine for about 90 seconds, leaving him bloodied. Valentine said he had to return to the hospital where he works to receive seven staples to close the wound on his head.
James said officers struck protesters with blunt instruments at least 50 times, unlawfully deployed pepper spray on at least 30 occasions and pushed or struck protesters at least 75 times.
The attorney general described the case of a Brooklyn protester named Luke Hanna, who was struck in the back of the head with a baton in June. James said Hanna, who required ten staples to close a gash on his head, was not arrested or charged.
Additionally, the complaint said officers arrested or detained hundreds of protesters, legal observers and medics without legal justification. The attorney general said 12 legal observers were detained for violating curfew during a June protest in Bronx even though legal observers and medics were exempted from the curfew order.
The lawsuit accused the NYPD of kettling, or corralling protesters so that they could not disperse -- and then making mass arrests.
James's office investigated complaints from incidents between May 28, 2020, and December 11, 2020, and found that officers conducted mass arrests without probable cause and "targeted and retaliated against First Amendment activity" frequently, the news release said.
James' lawsuit joins others filed by groups such as Legal Aid and the ACLU, which in October filed a federal suit against de Blasio, the NYPD and its leadership on behalf of 11 plaintiffs who claim they were subjected to brutality by police while peacefully protesting.
Last month, a report from the city Department of Investigation said the NYPD failed to anticipate the large number of protesters or violence during the demonstrations. That failure, combined with insufficient staffing and lack of training, led to poor judgment and excessive force.