Most of America's violent crimes and property crimes go unsolved, and many victims don't contact police at all

• Police across America have faced heavy criticism in recent weeks over instances of brutality and excessive force.
• But some policing critics have also noted that the country's law enforcement agencies are often unable to fulfill one of their main tasks: to solve crimes.
• Federal government data from 2018 show that just 46% of all violent crimes reported to police were "cleared" with an arrest, and 18% of property crimes were cleared.
• Beyond that, only an estimated 43% of people who were the victims of violent crimes reported the incidents to police.

A raging debate over policing in America has resurfaced old questions about the tactics and effectiveness of law enforcement agencies, and sparked a debate about whether the country even needs them at all.

The United States has seen weeks of anti-racism and anti-police brutality demonstrations in the wake of the death of George Floyd in police custody, and some have called for police departments to be defunded or even abolished altogether.

While the debate rages over the value and necessity of law enforcement, some critics have argued that though police exist to respond to and investigate crimes, they don't end up solving most violent and property crimes. Experts have also argued that under-policing can be just as harmful to communities as overly aggressive policing.

For instance, in the last 10 years, some 26,000 murders in major US cities went without an arrest, according to a Washington Post investigation. The newspaper said police attributed much of their difficulty solving the homicides to strained relationships with residents — for instance, the officers may be aware of the killer, but unable to convince witnesses to cooperate.

Low arrest rates are an issue not just for murders, but for most crimes in general. In 2018, the most recent year for which data is available, just 45.5% of all violent crime cases reported to police in America were "cleared," typically meaning a suspect was arrested, according to the FBI's Uniform Crime Reporting Program.

When it came to property crimes, the clearance rate was much lower, at just 17.6%.

Just 62% of murders and 33% of rapes are solved

The data suggest that most of the other 54.5% of violent crimes and 82.4% of property crimes in 2018 went unsolved, though there are a few caveats to the FBI's data that are important to note — namely, that it's possible some of those crimes will be solved in subsequent years for which the FBI has not yet published data.

As the Pew Research Center has noted, the FBI's clearance rate data is also incomplete. Law enforcement agencies across the country voluntarily report their crime and arrest data to the FBI, but it's not mandatory.

The FBI also breaks down the clearance rate by specific crime. For violent crimes, just 62.3% of murders, 33.4% of rapes, 30.4% of robberies, and 52.5% of aggravated assaults ended with arrests.

For property crimes, just 13.9% of burglaries, 18.9% of thefts, 13.8% of motor vehicle thefts, and 22.4% of arsons ended with arrests.

Furthermore, those figures only represent the arrest rate for crimes that are reported to police. The Bureau of Justice Statistics' National Crime Victimization Survey found that in 2018, the most recent year for which data was available, just 42.6% of people who were the victims of violent crimes reported the incidents to police.

For property crimes, just 34.1% of those who were victimized reported the incidents to police.

BJS said victims often avoid reporting crimes due to "fear of reprisal or getting the offender in trouble, believing that police would not or could not do anything to help, and believing the crime to be a personal issue or too trivial to report."