Exactly how many people are killed by the police each year? This question has been asked with increasing urgency in the months since Michael Brown was killed by Ferguson, Missouri, police officer Darren Wilson last August. Brown’s death energized a movement to reform American police practices, in particular the use of deadly force. That movement, under the banner “Black Lives Matter,” has directed the nation’s attention to police killings of unarmed black Americans and spurred numerous efforts to estimate the scale of the problem.

Still, a full year after Brown’s death, the government is without a reliable system for tracking police use of force. Experts say given the nature of the phenomenon and the difficulty of measuring it accurately, it’s not likely we’ll have one any time soon. Yet recent developments, including new proposed legislation and a White House initiative, could make tracking police violence a whole lot easier.

The Department of Justice is mandated by the Violent Crime Control and Law Enforcement Act of 1994 to “acquire data about the use of excessive force by law enforcement officers” and to “publish an annual summary of the data acquired.” William Sabol is in charge of the government arm ostensibly responsible for providing those numbers. As director of the DOJ’s Bureau of Justice Statistics he oversees the collection, analysis and dissemination of information on the operation of justice systems at all levels of government.

Sabol says the BJS is working to improve its knowledge of police behavior but can’t yet satisfy the public’s thirst for information.

“Policing involves a complex constellation of interactions between people engaged in a variety of behaviors,” Sabol said. “The BJS’s role is to try to characterize these incidents, measure them well and present the dependent variables for future analyses.”

Since Ferguson, the bureau has recommitted itself to moving forward on measuring not just police killings but all uses of force by police in the process of arrest, even yelling. “To get at questions of racial bias in policing, the BJS also plans to collect demographic data on the officers and civilians involved in these incidents, along with information about their interactions and the circumstances surrounding them,” Sabol said.

Gathering that data from the nation’s law enforcement agencies has proven no easy task. “Even if one takes something like a death, a death is ostensibly easy to capture, but when one says ‘death in the process of arrest,’ it introduces some subjectivity to the concept, and it presents measurement challenges,” Sabol said.

The BJS is not the only body attempting to measure police behaviors. For the past two years, UCLA’s Center for Policing Equity (CPE) has been working to develop the nation’s first database tracking national statistics on police behavior, including stops and use of force. That project, The Justice Database, has the highest volume of data among major nongovernmental efforts.

The Justice Database received funding from the National Science Foundation in 2013 to monitor police behavior and explore racial disparities in policing. So far, more than 40 national police departments and law enforcement agencies have signed on to report data. Its participating agencies represent more than half of all major cities and police more than a quarter of the nation’s population.

Police participation is one challenge to the research, but there are many others, CPE co-founder Phillip Goff said.

Indeed, there are about 18,000 law enforcement agencies in the United States, the vast majority of which are small, with fewer than 25 officers, many of whom have no significant training in research methods or statistical analysis. Compounding that, codes used for police reports and the reporting instruments themselves can differ dramatically from jurisdiction to jurisdiction, creating challenges for analysis once the data is obtained.

“It takes a lot of brainpower to figure out how to collect and measure evenly and consistently across jurisdictions,” Goff said. “Because we’re getting data on pedestrian stops, vehicle stops, use of force and all other crime data, we need to make sure that we’re controlling for the right things.”

While the BJS and CPE are working to build systems that can comprehensively measure police behavior, news media has stepped in to satisfy the public’s desire for information.

Over the past few months, The Guardian and The Washington Post have published reporting projects that measure the number of civilians killed by police. The Guardian’s count for 2015 stands at 690, and the Post’s, which tracks deaths from police shootings in particular, is at 581. Both projects rely on data provided by news outlets, research groups, and the open-source reporting projects Fatal Encounters and Killed By Police.

The Guardian’s and Post’s projects have captured the public’s attention, but Sabol says they lack the rigor needed to provide lasting answers. The projects are, after all, works of journalism designed to offer estimates based on available data, not official measurements.

“The Washington Post and Guardian projects miss a lot of information,” he said. “And even the discrepancies between the two point out that the effort has to be multifaceted. No single collection in the effort is going to answer all the questions completely, so it then becomes the responsibility of an independent arbiter to try to make some sense of what this all means. That’s very complicated stuff.”

Before leaving his post as attorney general in April, Eric Holder said the federal government, his agency specifically, should be the one collecting “better, more accurate data” on police behavior. “The troubling reality is that we lack the ability right now to comprehensively track the number of incidents of either uses of force directed at police officers or uses of force by police,” he said. “This strikes many — including me — as unacceptable.”

In early June, Sens. Barbara Boxer of California and Cory Booker of New Jersey announced a new bill, the Police Reporting Information, Data, and Evidence Act of 2015. As written, the PRIDE Act seeks to push data collection efforts forward in part by mandating that states record and report to the DOJ every case in which an officer shoots, causes serious bodily harm to or kills a civilian. To encourage participation, the bill authorizes the creation of new federal grants. The PRIDE Act expands on an existing law that requires states to report shootings and uses of police force only when they result in a death. The bill is currently in committee.

“I’ll be interested to see how it moves through Congress,” said Goff, who is skeptical about the bill’s chances of becoming law. “Part of the reason legislation hasn’t moved forward is pushback from local law enforcement and reasonable concerns over the logistics of enforcement.”

The key to collecting reliable, comprehensive data is, of course, the participation of individual police agencies. Officers ultimately are tasked with recording instances where force is used against a civilian. Without their participation, it’s unlikely that the PRIDE Act would yield reliable, comprehensive data. For that reason, legislators might be shy about putting state governments on the hook.

“In principle, I agree that police departments should make the information public, but the language of the bill puts the onus on the state,” Sabol said. “There’s still a question for me of what the law requires versus the nature of the problem we’re trying to measure and where it actually resides.”

Perhaps following that line of reasoning, the White House has been taking quiet steps to rally resources around the sticking points in the data collection process. Launched to little fanfare in May, the Police Data Initiative is focused on shoring up the data collection and reporting efforts in 21 jurisdictions around the country, mostly major cities including Cincinnati, Philadelphia and Oakland, California. It’s something of a pilot program and is bringing together developers, police chiefs and researchers to develop better collection practices, high-tech reporting tools, and means for analysis and dissemination of data on uses of force, pedestrian and vehicle stops, and officer-involved shootings.

Jenny Montoya Tansey is director of safety and justice at Code for America, a nonprofit agency that develops open-source technology to help streamline government services and processes. Her organization is one of many involved in the Police Data Initiative and was enlisted by the White House to help create a best-practices playbook for data transparency, as well as software for the extraction and transfer of data from existing data sets and reports.

“In communities across the country, there is a broad consensus that our justice system is not working,” Montoya Tansey said. “They need the ability to increase transparency around the inner workings of the justice system, increasing accountability and making possible more productive public dialogue about these pressing issues.”

Like other efforts, private and public, the Police Data Initiative will likely take some time before it yields a framework for collection, analysis and dissemination of policing data that can be expanded across the nation’s many law enforcement agencies. Assembling key stakeholders, however, just might be the necessary first step to creating a comprehensive, sustainable system that can yield reliable data.

“I’d describe the Police Data Initiative as an attempt to get everyone to play in the same sandbox. It’s a good thing,” Goff said. “Private, public — we’re all taking on different chunks, and we’re going to have to answer these questions together.”