Since Hurricane Katrina devastated New Orleans in 2005, national taxpayers have poured billions into the Crescent City’s infrastructure. But recent news reminds us that New Orleans needs more than outside money to flourish: it needs to create a safe and just environment for its citizens.

Even as it has constructed new levees to protect New Orleanians from future floods, Washington has spent the past few years mopping up the mess from New Orleans’s broken justice system. Last week, a federal judge sentenced two former police offers for killing civilian Henry Glover in the days after Katrina and burning Glover’s body to cover up the crime. Last week, too, a federal jury found a police captain guilty of a comparatively run-of-the-mill corruption scheme. And this week, a federal judge will choose jurors for the trial of two officers in the pre-Katrina beating death of civilian Raymond Robair and the attendant cover-up.

In case anyone thought that local cops’ crimes were a series of random, one-off events, a new report puts that idea decidedly to rest. The Justice Department’s 158-page study on the New Orleans Police Department, published last month, concluded that the NOPD routinely “engages in patterns of misconduct that violate the Constitution and federal law.” Anything that a police department should do, the report suggests, the NOPD does wrong or not at all. On basic practices like interrogating suspects, questioning witnesses, and filing reports, for instance, officers are unqualified, untrained, or both. Patrolmen use excessive violence, from punching to shooting, apparently without realizing, in many cases, that rules exist to govern such actions.

Commanders only superficially subscribe to modern strategies and tactics. New Orleans has long paid lip service to Compstat, the crime-data collection and analysis system that New York City pioneered in the 1990s. In New Orleans, the NOPD collects crime arrest data but doesn’t use them properly; the department obsesses over misdemeanor arrests, for example, often related to old traffic violations, but the arrests don’t lead to information, crime prevention, or convictions, as they should. In 2009, one-third of the NOPD’s 60,000 arrests were of “people with outstanding traffic or misdemeanor warrants” from neighboring counties, the report notes, “for such infractions as unpaid tickets.”

Problems compound problems. Young people with employment options don’t want to join a dysfunctional police department, despite competitive pay. Last year, the department discharged 60 percent of its recruiting class because trainees couldn’t make the grade. Corruption is endemic. Its “aorta” is the city’s system of paid “details”—officers working as private guards while wearing police uniforms and using police equipment. Officers often negotiate such deals (including compensation) themselves, making their services available to private companies or entire neighborhood associations. With access to this private security, New Orleans’s wealthier citizens often lack a civic stake in the police department’s success. In this they are very different from New Yorkers, whose pressure became a key factor in Gotham’s successful fight against crime. As the DOJ report points out, through off-duty neighborhood and corporate patrols, New Orleans has “privatized officer overtime,” with officers “working details in the areas of New Orleans with the least crime.”

In one sense, the report is good news: Mayor Mitch Landrieu asked for it as one of his first actions on taking office last May. He understands that unless he fixes the police department, he can’t achieve his goal of reducing violent crime. “The city of New Orleans is not safe,” Landrieu said days after his election. “When New Orleans is best known for crime, something is drastically wrong.” This statement may seem obligatory in a city recently called the nation’s “most murderous” by its own newspaper, the Times-Picayune. Last year, New Orleans suffered 175 murders in a city of 365,000, giving it a per-capita rate of 48 per 100,000 residents, four times that of midsize cities like Boston or Nashville, and seven times New York’s rate.

But pledging to cut the body count is almost revolutionary in New Orleans. City officials have previously chosen to deny or justify the bloodshed—saying that it’s rooted in poverty, for example—rather than confront it. Landrieu, by contrast, pledged to hire a top-notch police chief, and he sought advice from top crime fighters like NYPD commissioner Ray Kelly and former LAPD chief William Bratton in making his choice: New Orleans native and 21-year NOPD veteran Ronal Serpas. Nearly two decades ago, during the only other time in the NOPD’s modern history that the city tried to fight corruption—after a female police officer murdered a colleague as well as the owners of a store who had hired the colleague to do a private-security detail—Serpas served as a key deputy. Before assuming the top spot last year, Serpas spent five years heading the Nashville police department. His tenure there saw a drop in violent crime, though from already declining levels, and in a city with a functioning police department.

In the ten months since taking over in the Big Easy, Serpas has made some good moves. He’s toughened recruiting standards, requiring candidates to have college credits or military experience; and he’s instituted a no-tolerance policy, promising to fire any officer who lies about anything. He’s reorganizing the department, too, directing commanders to compile statistics not just for the sake of having them, but for practical use in reducing crime. Similarly, Serpas has directed commanders to ensure that officers target and question suspects for the purpose of preventing crimes—rather than giving them credit for racking up unrelated misdemeanor arrests that do nothing to curtail the violence.

Serpas told me last month that he wouldn’t shy away from “aggressive” policing. “Violent criminals need to know that law enforcement will confront them legally and professionally,” he said. The DOJ report won’t discourage him from strategies like stopping and questioning suspects to confiscate illegal weapons that could be used in robberies and murders. He will carry out such practices, he pledged, “while respecting the rule of law.”

Yet so far, progress remains more promise than reality. During the first two months of 2011, the city’s murder rate soared nearly 40 percent. Two weekends ago, four people were shot to death. In February, a 22-year-old student named Lars Stiaes, an injured veteran of the war in Afghanistan and the nephew of a state lawmaker, was murdered during a street robbery.

Troublingly, Serpas can fall into the habit of explaining away crime. He has said that it’s hard to prevent murders when murderers know each other and are motivated to kill. “Serpas sounds not all that different” from his predecessors, wrote Times-Picayune columnist Jarvis DeBerry last month, criticizing the chief’s propensity to talk like a “social worker” and explain “that murders are high because New Orleans is awash in so much dysfunction. Yes, we know,” DeBerry wrote. “Nobody who lives here is unaware of our social ills.”

It’s true that most murderers know their victims and seek them out to settle disputes, which are often drug-related. But this is true everywhere, including New York, which has brought crime down 77 percent since the mid-1990s. Moreover, New Orleanians need no encouragement from Chief Serpas to maintain their poisonous habit of compartmentalizing violence. For years, residents have rationalized the city’s murder rate by noting the heavy involvement of drug dealers; they get what they asked for, goes the reasoning.

Mayor Landrieu has only so much time before middle-class and wealthier citizens conclude that his quest for a just, safe city is an impossible one—and retreat from their post-Katrina civic activism. For New Orleans’s sake, tangible improvements are needed now.

Nicole Gelinas is a contributing editor to the Manhattan Institute’s City Journal. She lived in New Orleans in the mid-nineties and visited again last month.