Mayor Mitch Landrieu's administration wanted to delay the decree, while the judge weighed the request to toss out the entire decree.
But Judge Susie Morgan ruled that the city can no longer stall on moving forward with the mandated reforms. She said the city failed to show how implementing the decree now would cause "irreparable harm."
The city had argued that the Justice Department misled the city and that the consent decree would be a huge financial hit to the city, especially amid a battle over another consent decree concerning the city's prison. Landrieu has said the city doesn't have the tens of millions of dollars to fund both matters.
Judge Morgan noted that any and all reforms will certainly cost money.
The city's request to vacate the decree altogether remains a pending matter. Morgan touched upon this in her ruling, noting that the city "has not made any showing whatsoever that it is likely to succeed" in its attempt to toss the decree out.
The Department of Justice has another week to respond to the city's allegations. After that, Morgan will weigh the matter and make a final ruling.
Landrieu estimates it will cost roughly $11 million annually for the next four or five years to implement the reforms.