The U.S. War on Marijuana is not just costly, time-consuming and unnecessary -- it's also racially biased, according to a new report.

In recent years, several states have passed laws that decriminalized marijuana, and a majority of Americans now support legalizing the drug. Yet between 2001 and 2010, there were over 8 million pot arrests in the U.S. What's worse, the authorities making the arrests were targeting black Americans far more than whites.

According to a new study from the American Civil Liberties Union, which tracked marijuana arrests by race and county in all 50 states and the District of Columbia, black and white Americans use marijuana at about the same rate. However, blacks were nearly four times as likely than whites to be arrested on charges of marijuana possession in 2010.

In Washington D.C., Iowa, Minnesota and Illinois, blacks were 7.5 to 8.5 times more likely than whites to be arrested for possessing pot.

Most of the people being arrested weren't drug kingpins. Fifty-two percent of all drug arrests in 2010 were for marijuana, and according to the ACLU's analysis, most of the arrestees were in possession of small amounts of the drug.

Having a black president hasn't eased this racial disparity, either. During President Barack Obama’s first three years in office, the arrest rate for marijuana possession was about 5 percent higher than the average rate under President George W. Bush, The New York Times reported.

Obama's first term in office was also marked by an economic recession, a soaring deficit (due to the cost of the Bush tax cuts and two wars) and numerous budget battles that threatened to cause state and federal government shutdowns. In the midst of this, the costs of the War on Marijuana continued to rise.

In 2010, states spent an estimated $3.6 billion enforcing marijuana possession laws, which was a 30 percent increase from a decade earlier. Such a large amount of funding provides a strong financial incentive for police to make arrests and boost their crime-fighting statistics, the ACLU reported. In fact, that same year, more people were arrested for marijuana possession than for all violent crimes combined.

"In the past 75 years we have seen mounting evidence of the benign nature of the marijuana plant, and its tremendous potential for medical development," Amanda Reiman, policy manager for the Drug Policy Alliance said in 2012. "But the rampant misinformation about the effects of marijuana USE is dwarfed by the lifetime of suffering that a marijuana CONVICTION can bring."

Click here to download the full report.

