By Michael Nam

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Recent independent data from The Guardian showed that Black Americans were twice as likely to be killed by police than white Americans despite a major difference in population sizes. The Guardian’s ongoing effort to count this year’s police-related deaths and a report from the Department of Justice shows just how unreliable the FBI’s data may actually be.

The Justice Department’s Bureau of Justice Statistics estimates that nearly half of all police-related homicides are undercounted in the data collected from police:

The variation in methodologies resulted in a significant underestimate of the annual number of arrest-related deaths, including both homicides by law enforcement officers and other types of civilian deaths.

There are two significant factors limiting access to clear data on the number of deaths in police custody: the voluntary nature of reporting and the definition of what kind of deaths should be included in the reporting.

Only a small percentage of police agencies in the U.S. have reported fatal shootings by cops since 2011, and when expanding the definition of what kinds of deaths should be included in reports to the FBI, a huge difference in the number of police-related homicides can be seen as well, according to Business Insider.

BJS victimization statistics chief Michael Planty pegs the number at about928 per year on average over an eight-year span from 2003-2009 and 2011. For comparison, the FBI calculated 423 homicides per year on average over that same span.This 545-person gap in police homicides appears because the BJS report included the number of arrest-related deaths, or deaths that occur during an interaction with law enforcement personnel in the process of arrest or attempted arrest.

As of the posting of this story, The Guardian’s own count of deaths at the hands of police stands at staggering 512 with more than half of 2015 remaining.Thus far, 40 percent of unarmed individuals killed by police were Black (who make up only13 percent of the population) versus 37 percent that were white (63 percent of the population). While some pundits have argued that the death rate of Black menat the hands of police is understandable due to violent crime statistics showing that population to be both a greater threat and at greater risk, the same reasoningshould hold true when considering the lack of threat unarmed Blackpersons should imply to armedpolice officers.

Overall,the lack of an accurate and wide-ranging database has been detrimental in forming national policy on the issue of police brutality. The federal government being in the dark about how law enforcement is involved with homicides of all kinds has even reached the attention of lawmakers like Sen. Cory Booker and Rep. Barbara Boxer, both of whom are attempting to change the reporting system.

“The first step in fixing a problem is understanding the extent of the problem you have. Justice and accountability go hand in hand — but without reliable data it’s difficult to hold people accountable or create effective policies that change the status quo,” Sen. Booker said in a statement.

The initiative by Booker and Boxer would require policing agencies to report to the Attorney General on “use of force incidents” including the following data:

The gender, race, ethnicity, and age of each individual who was shot, injured, or killed; The date, time, and location of the incident; The number of officers and number of civilians involved in the incident; Whether the civilian was armed with a weapon; and The type of force used against the officer, the civilian, or both, including the types of weapons used.

Where data on policing can be disaggregated, they have often showed significant racial bias, such as in the case of the number of shootings mentioned previously, or even in something less lethal such as targeted traffic stops in Ferguson and in Missouri as a whole.