NYPD Inspector Rodney Harrison, center, and Officer Jimmy Hughes, left, stop three individuals in the stairwell of 212 West 129th street. (Photo by Joe Marino/NY Daily News via Getty Images)

Beginning September 21, NYPD officers will have to issue "receipts" to anyone they stop, but do not arrest, and offer an explanation for the encounter. Officers will also have to fill in their badge number and provide contact information for the Civilian Review Board, in case citizens want to file a complaint.

It appears to be a stunning reversal for a police department that just four years ago stopped over half-a-million innocent people under the city's stop-and-frisk policy, the vast majority of whom were Black or Latino.

But the move is coming under fire from police reform advocates, who say it doesn't go far enough, and from New York City police unions, who call it a "new burden" on officers.

The policy comes out of a 2013 federal class-action lawsuit , Floyd vs. City of New York, in which a judge found that the NYPD unfairly targeted minorities for "stop and frisks." The ruling empowered federal monitor Peter Zimroth to keep tabs on the NYPD, oversee reforms, and make changes to police protocols.

A number of his recent recommended changes in the NYPD Patrol Guide — including the stop and frisk receipts — were approved by federal Judge Analisa Torres on Monday.

The NYPD confirmed the new policy will go into effect at the end of next month.

"Based on the recommendations of the federal judge and court-appointed monitor, a new patrol guide procedure governing stop and frisk provides a new explanatory receipt to persons stopped but not arrested, baring exigent circumstances," the NYPD said in a statement provided to VICE News.

In some ways, the new guidelines resembles the "Right to Know Act," a reform bill being considered by the New York City Council. Earlier this summer, Police Commissioner Bill Bratton rejected the bill . Testifying before the council in June, Bratton said that any legislation requiring cops to provide a reason for stops represented an "'unprecedented intrusions" into police business.

"Imposing conditions on daily officers' conduct at the operational level...raises new and serious legal and operational questions," Bratton said at the time.

Communities United for Police Reform, a coalition of dozens of grassroots groups pushing for changes in the NYPD, championed the Right to Know Act. Monifa Bandele, a member of the group's steering committee, said that the new receipt policy reveal's Bratton's earlier objection to be "disingenuous."

"He said it was bad idea...but then they are going ahead and piloting something really similar," she told VICE News.

Although Bandele and Communities United for Police Reform support the principal of the receipt policy, she says it diverges from the legislation she and her coalition support in two significant ways.

The new policy requires officers to issue receipts only during technical "stops," leaving out thousands of police encounters, such as traffic ticketing, and routine questioning. This loophole will allow police to remain anonymous, Bandale says, skirting the intention of the "Right To Know Act."

She also worries that officers will not clearly write their badge numbers on the new "receipts. The legislation her group proposed would have forced officers to carry a specific business card that would clearly display their contact information.

Though the differences between the legislation Communities United pushed, and the announced reform may appear minor, Bandale says that the new initiative is fatally flawed and "not even better than nothing at all."

"The way this came about goes behind the backs of the legislative and democratic process," she said. "We weren't consulted at all."

The mayor's office, however, insisted that the grassroots organizations had been included in the conversation.

"The community has had input through the remedial process overseen by the court," Deputy Press Secretary Monica Klein told VICE News.

But Councilman Ritchie Torres of the Bronx, a champion of the "Right To Know Act," was also troubled by how the new reforms came about.

"It seems to me that only the threat of judicial intervention can force reform. Everything else to me seems inadequate," he told Capital New York.

The new receipt policy was ironed out by Zimroth and the NYPD as an internal update to the patrol guide.

"As the department itself acknowledges, the current version of the patrol guide section on investigative encounters... does not provide sufficient guidance or instruction," Zimorth wrote to federal Judge Analisa Torres Monday, to explain the rationale behind the new rules.

Zimorth wote that the new policy will require officers to identify on the spot a specific reason for performing a stop. The officer will be asked to check a specific box on a receipt that includes categories such as "acting as a lookout," "engaging in a drug transaction," and "matches a specific suspect's description."

Meanwhile, the head of one of the most powerful police unions — the Patrolmen's Benevolent Association (PBA) — Patrick Lynch, slammed the proposal.

"[It's] just one more item on the ever-growing list of anti-public-safety measures, " he said in a statement. "[It] will put an end to proactive policing."

The PBA's opposition to the measure drew criticism from some policing experts.

"The suggestion that accountability hurts crime fighting is based on the faulty belief that that only way to reduce crime is through aggressive, disrespectful, and unconstitutional policing,"

Alex Vitale, a criminal justice expert at Brooklyn College, told VICE News.

When contacted by VICE News, the PBA did not elaborate on how the measure would negatively impact public safety.

Despite objections on both sides, the new rules have the potential to change the tenor of police interactions.

"This new procedure is no cure-all for the problems of discourteous, abusive, and excessive policing," Vitale said. "But it is a step towards greater transparency and accountability, and could play a role in reducing some of the worst practices by officers."

The policy is the latest of several reforms enacted by Mayor Bill DeBlasio's administration since the federal class-action lawsuit was settled in 2013. Deblasio has called for a pilot body camera program, and pushed to give officers more time to walk their beats in neighborhoods. In the last year, stop-and-frisks in New York plummeted to about 50,000 annually. Nearly 80 percent of those stopped are innocent of any crime.