Every night the images of nationwide protests play out on local and national news, and in the mornings they’re displayed colorfully on the front pages of newspapers: The American police officer posing as a soldier, clad in a military-grade helmet, shield, and mask, clinging to a rifle, perhaps riding in an armored vehicle, confronting citizens armed with bandanas, surgical masks, and water bottles. 

Over the past 30 years, Americans have grown accustomed to this presentation of the police as SWAT teams, distinguishable only in uniform from those being deployed around the world, show their force during protests, drug searches, and other special emergencies. 

That’s largely because of the 1033 program, a federal plan that authorizes the Department of Defense (DoD) to pawn off its outdated equipment, from grenade launchers to bayonets to armored vehicles, to local police units for just the cost of shipping. 

Since its permanent inception in 1997 (it began as a temporary response to the war on drugs in 1990), $7.4 billion worth of property has been transferred from the U.S. military to more than 8,000 law enforcement agencies, according to the Law Enforcement Support Office, a DoD group that oversees the program. In 2019 alone, about $293 million worth of military equipment was transferred to police around the country. 

Now a new, bipartisan piece of legislation, introduced by senators Brian Schatz (D-Hawaii), Lisa Murkowski (R-Alaska), Kamala Harris (D-Calif.), and Rand Paul (R-Ky.), would prohibit the transfer of military equipment to law enforcement agencies through the program. Banned items would include tear gas, armor-piercing firearms and ammunition, bayonets, grenade launchers and grenades, combat-tracked vehicles, and drones. The legislation still allows for the military to transfer office supplies and body armor. 

The bill, Schatz told Fortune, would also require the Department of Defense to submit annual reports to Congress with detailed accounting of any transfers made. 

This detailed accounting, he said, was key. But accountability has long been a problem for the program.

In 2017, an investigation by the Government Accountability Office found that shipments of $1.2 million in military-grade equipment including night-vision goggles, simulated rifles, and simulated pipe bombs, were authorized to go to a fake police department set up as part of the investigation. In total, the DoD agreed to ship 100 controlled items to the fictitious agency. The investigation concluded that the program had little oversight or accounting for controlled items like aircraft, armored vehicles, and firearms. The DoD implemented a vetting program through the National Crime Information Center database in response to the report’s release. 

But the flow of information is still lackluster. A recent study, led by Louisiana State University political science professor Anna Gunderson, made an attempt to look at data made public by the Department of Defense around the transfer of weapons to determine if the program has been effective in increasing public or police safety. The study found such large gaps in reporting that it was unable to come to any serious conclusions. 

Gunderson told Fortune that when she started writing her paper two years ago she realized that the data wasn’t consistent: She found large gaps and discrepancies in the recorded pricing for the same items. She was surprised to learn that several local police forces had been suspended from the program because they had lost high-grade military equipment sent to them or couldn’t account for it. There was no reporting on whether officers who received equipment were trained to use it—there is currently no requirement for training.

In 2014, after the unrest in Ferguson, Mo., the program came under scrutiny. A Freedom of Information Act request sent by NPR revealed the first publicly available data about where equipment was going, and the Obama administration subsequently created a new policy to stop the most aggressive weapons—aircrafts and tanks—from going to police departments. The policy also required “a clear and persuasive explanation of the need for the controlled equipment,” as well as reporting and oversight for items distributed. 

But the order was immediately overturned by the Trump administration, which cited two reports based on the 2014 FOIA data that concluded that the equipment had aided in police safety.

“Those restrictions went too far,” then Attorney General Jeff Sessions said of the gear that he referred to as lifesaving. “We will not put superficial concerns above public safety.”

Subsequent data, however, said Gunderson, showed that those studies were fundamentally flawed. “The bottom line is that we have no evidence that militarization affects crime in the way that we thought it had. Any finding that we have is based on this flawed data, so we can’t really say for sure that there’s any influence,” she said. 

A slew of recent studies, including one by Gunderson, have concluded that the proliferation of military gear does not increase public or police safety, but rather it incentivizes officers to use undue force and disproportionately hurts Black Americans.

One 2017 study found a significant correlation between equipment transfers from the 1033 program to police departments and fatalities from officer-involved shootings. Not only did the program cause the police to act more violently, the analysis concluded, but it actually increased the use of violence toward the police.

Another study, by Princeton University’s Jonathan Mummolo, studied SWAT team deployment data in Maryland and found that militarized police units were more often deployed in neighborhoods with large percentages of Black residents, even after controlling for local crime rates. The “vast majority” of SWAT deployments were for nonemergency situations like serving search warrants, the data showed. When a SWAT team did show up in response to a violent crime, he found a 6.5% increase in within-agency violent crimes, on average, hurting officer safety.

Mummolo also conducted three nationwide surveys on how police militarization impacts police reputation with the public. He found that showing people photos of militarized police forces led to a 3.2 point drop in the desire to have police patrols in respondents’ own neighborhoods and a 4 point drop in the desire for police funding. 

“Militarized policing can impose reputational costs on law enforcement, likely in unintended ways,” wrote Mummolo. “This is troubling, since prior work shows that negative views of police inhibit criminal investigations and are associated with stunted civic participation.”

Schatz, meanwhile, says that his bill has bipartisan support, and he’s hopeful it can pass. “The data is clear,” he told Fortune. “Giving police departments military weapons does nothing to keep people safe. Instead, it has led to more police shootings and deaths.”

When asked for comment about accountability and the bill, the Department of Defense told Fortune to look at the frequently asked questions already posted on its site, where a broad oversight policy is outlined. The department did not respond to specific questions.

It’s important to note that only a small percentage of the items shipped to police departments under the 1033 program are “controlled,” and the vast majority of items include things like office chairs, vests, and other “uncontrolled” goods. There are also a number of other programs that police precincts use to obtain military gear from the federal government that operate under far more obscurity than 1033. 

The 1122 program allows state and local governments to purchase discounted military gear from the Pentagon to support “counter drug, homeland security, and emergency response operations.” There is no data about the program readily available online. 

“The reason we hear so much about 1033 is that you can literally Google it and pull up the data, but that’s not the case for these other programs,” said Gunderson.

Earlier this month, Schatz released further legislation to increase oversight on two other similar programs, the Department of Justice’s Byrne JAG grant program and the Department of Homeland Security’s Preparedness grants, which provide money to aid in law enforcement and are used to purchase military-grade weapons for local police forces.