In the weeks after the death of Michael Brown in Ferguson, Mo., images of officers training rifles on crowds of protesters from the turrets of armored vehicles became a potent symbol of the distrust between law enforcement and citizens in Ferguson -- and elsewhere.

Now, civil rights and civil liberties advocates are calling on the Obama administration to respond to the events in Ferguson by discouraging police from relying so heavily on military equipment and tactics.

Several federal programs are helping local law enforcement to acquire heavy weapons, either by making funds available or by providing the equipment directly. One program at the Pentagon transferred surplus military equipment worth nearly half a billion dollars to local police last year. Grants provided by the Department of Homeland Security total another $1 billion, and Holder's department provides hundreds of millions more.

"We do not condition that money on requiring real change in policing," said Sherrilynn Ifill of the National Association for the Advancement of Colored People in a press conference on Tuesday. "Taxpayer money to local police departments should come with the condition that the police take responsibility for improving."

President Obama requested a review of these programs after Brown's death. An administration official told The Washington Post that the review would be led by White House staff and would include several cabinet departments.

"This equipment flowed to local police forces because they were increasingly being asked to assist in counterterrorism," said Attorney General Eric Holder in a statement when the review was initially reported. "But displays of force in response to mostly peaceful demonstrations can be counterproductive. It makes sense to take a look at whether military-style equipment is being acquired for the right purposes."

Critics have long argued that the Obama administration should place more rigorous requirements on police departments asking for money or equipment.

There's no law requiring that the administration give money and equipment to any police department that requests it, and Congress has given federal officials wide latitude in determining how the money is distributed. So far, the executive branch has mostly refrained from using that power to pursue a law-enforcement agenda.

A letter from the NAACP, the American Civil Liberties Union and other advocacy groups laid out a range of recommendations after Brown's death. Several lawmakers, including Sen. Rand Paul (R-Ky.), have also criticized what they see as the excessive and wasteful militarization of the police, but Obama doesn't have to wait for new legislation.

The ACLU has called for a moratorium on the Pentagon's program, which transfers surplus military equipment, arguing that the Pentagon should not provide local police with armored personnel carriers or automatic weapons.

Meanwhile, the Justice Department is conducting an investigation to determine whether there is a pattern of racial discrimination at the Ferguson Police Department in general. The investigation could lead to a wholesale reform of the department, as have similar probes in a handful of other jurisdictions. This kind of investigation does not have much effect on law enforcement in other communities nationwide, though.

Although no conclusions have been announced publicly, at least so far, the review of the federal government's financial support for police departments might have broader consequences. Advocates hope that federal grant applications could be an occasion for police administrators to take a careful look at their departments' practices in a broader way.

The administration could, for example, mandate that any department receiving federal support equip its officers with body cameras.

Another approach would be to require departments to provide data showing that their officers do not discriminate by race in stopping drivers. Missouri's attorney general issued a report last year finding that Ferguson's police officers were twice as likely to arrest black drivers as white drivers during traffic stops. Departments with wide racial disparities in enforcement would not be eligible for federal money.

Alternatively, the federal government could require police officers to undergo training in how to deescalate violent altercations with people of other races, or people who are mentally ill, without using lethal force.

"At the end of the day, we are looking at the culture, the police culture," said Kanya Bennett, an attorney at the ACLU, in an interview. "In order for us to appreciate and get a full sense of the sort of abuses that come along with this military equipment, we need to step back and assess what's going on."

"Money is a powerful incentive for change in this country, and always has been," said the NAACP's Ifill. "We're suggesting it's time we applied that to law enforcement grants."

In several cases, the tactics that accompany military-grade weapons have led to the deaths of innocent people. A 7-year-old died in a Special Weapons and Tactics raid in Detroit in 2010, when officers forcibly entered the house where she was sleeping, deploying a flashbang and firing a bullet that struck and killed her.

That said, Wilson's patrol car was an ordinary Chevy Tahoe, and there's no reason to think that his interaction with Brown would have ended any less tragically if local police carried less heavy equipment. It might be too much to expect reforms at the federal level to address all of the issues related to police shootings.

Body cameras are expensive, noted Denver Police Capt. Tracie Keesee, and collecting comprehensive data is not always the best use of every officer's time.

Keesee is part of a project at the University of California, Los Angeles that aims to make data on policing and racial profiling more readily available to researchers. Many police chiefs, she said, would probably decide to make do without the federal money.

She also noted that cops would resent the interference from Washington in how they work. Policing in the United States, she said, "has always been about local control."

"I think there's always been this hesitancy, because of local control, to say, 'You can't get this money,' " Keesee said.