NEW ORLEANS, La. — A court-supervised agreement Tuesday to overhaul the New Orleans Police Department will require the troubled agency to implement the most sweeping police reforms ever negotiated by the Justice Department.

Attorney General Eric Holder joined Mayor Mitch Landrieu in announcing the signing of a federal consent decree designed to clean up a police force that has been plagued by decades of corruption and mismanagement. The department came under renewed scrutiny following a string of police shootings in the chaotic aftermath of Hurricane Katrina in 2005.

The 124-page agreement spells out a series of strict requirements for overhauling the police department’s policies and procedures for use of force, training, interrogations, searches and arrests, recruitment and supervision.

Holder said the agreement is the most wide-ranging in the Justice Department’s history and resolves its allegations that New Orleans police officers have engaged in a pattern of discriminatory and unconstitutional activity.

“There can be no question that today’s action represents a critical step forward,” Holder said. “It reaffirms the Justice Department’s commitment to fair and vigorous law enforcement at every level.”

Landrieu estimates the city will pay roughly $11 million annually for the next four or five years to implement the reforms. He expressed confidence that the agreement will produce “the new NOPD.”

“There is no problem here that cannot be solved,” he said. “We can and we must change, and we now have a clear roadmap forward.”

A federal judge must approve the agreement and oversee its implementation. Among its provisions:

— All officers will be required to receive at least 24 hours of training on stops, searches and arrests; 40 hours of use-of-force training; and four hours of training on bias-free policing within a year of the agreement taking effect.

— All interrogations involving suspected homicides or sexual assaults will have to be recorded in their entirety on video. The department also will be required to install video cameras and location devices in all patrol cars and other vehicles within two years.

— The department will be required to completely restructure the system for paying officers for off-duty security details, develop a new report format for collecting data on all stops and searches and create a recruitment program to increase diversity among its officers.

— The city and Justice Department will pick a court-supervised monitor to regularly assess and report on the police department’s implementation of the requirements.

— The city and police department can ask a judge to dissolve the agreement after four years, but only if they can show they have fully complied with its requirements for two years.

The Justice Department has reached similar agreements with police departments in Los Angeles, Cincinnati, Pittsburgh, Oakland and Detroit. But the scope of the New Orleans consent decree is billed as the broadest of its kind and includes requirements that no other department has had to implement.

For instance, the agreement requires officers to respect that bystanders have a constitutional right to observe and record their conduct in public places. Its “bias-free policing“ provisions, which call for creating a policy to guide officers’ interactions with gay, lesbian, bisexual and transgender residents, also are believed to be unprecedented for a police department’s consent decree.

Holder said Landrieu and Police Superintendent Ronal Serpas didn’t wait for the agreement to be signed before instituting reforms.

“The problems that we have identified were many years in the making and preceded this current administration,” Holder said. “They are wide-ranging and they are deeply-rooted. Sustainable reform will not occur overnight, but we can all be encouraged that it is already happening here thanks to the leadership of Mayor Landrieu, Chief Serpas and so many others.”

Tuesday’s announcement comes on the eve of President Barack Obama’s visit to New Orleans. Obama is scheduled to deliver a speech at the National Urban League’s annual conference on Wednesday.

Last year, the Justice Department issued a scathing report that said New Orleans police officers have often used deadly force without justification, repeatedly made unconstitutional arrests and engaged in racial profiling. The report also found that the department has long failed to adequately protect New Orleans residents because of numerous shortcomings, including inadequate supervision.

At the time, Landrieu said many of the problems identified by the report were exposed by Katrina but existed for years before the storm smashed levees and plunged the city into chaos.

Rafael Goyeneche, head of an independent police watchdog group in New Orleans, said previous efforts to reform the department lacked the teeth and the strong federal oversight of a consent decree. The city will have to spend millions of dollars to implement the reforms, paying for training, equipment and oversight costs, Goyeneche said.

“This is going to be a living document that will shape the future of not just the New Orleans Police Department but of the entire criminal justice system, probably for the next eight to 10 years,” he said. “This is not going to be an inexpensive item for the city to absorb.”

The Justice Department’s civil rights division also launched a series of criminal probes focusing on police officers’ actions during Katrina’s aftermath.

The investigations resulted in charges against 20 officers, including five who were convicted last year of civil rights violations stemming from deadly shootings of unarmed residents on a New Orleans bridge less than a week after the 2005 storm’s landfall.

The officers convicted in the Danziger Bridge shootings were sentenced to prison terms of up to 65 years. Five others pleaded guilty to engaging in a cover-up plot that included a planted gun, phony witnesses and fabricated reports.

Goyeneche, president of the Metropolitan Crime Commission, said prior reform efforts merely “drove some of the problems underground for a period of time.”

“It didn’t really remove them. It didn’t change the systemic culture of the police department,” Goyeneche said.

Mary Howell, a New Orleans attorney who has frequently represented victims of police abuse, cautioned that the consent decree will not be a permanent solution to the department’s longstanding problems.

“Consent decrees have lives of their own, too, and they end at a certain point,” she said. “Everything we do now needs to be geared towards the day when we no longer have that direct federal oversight.”

Keith Twitchell, the head of the Committee for a Better New Orleans, a community organization, said the consent decree was long overdue but won’t necessarily result in a reduction in crime.

“Crime is just a symptom. We still have to find the cause,” he said. He said improving schools and the economy must be priorities in the city’s efforts to combat crime.