A sprawling new report from the American Civil Liberties Union argues that the war on cannabis disproportionately affects African-Americans, and makes the case for ending arrests for marijuana possession. The group’s 185-page study, called “The War on Marijuana in Black and White,” finds that black people are 3.73 times more likely to be arrested for possession than whites, even though people of both races consume marijuana at roughly the same rate.

Furthermore, the racial gap in arrests actually widened between 2001 and 2010. Researchers said racial profiling and other discriminatory law enforcement practices were largely to blame.

“State and local governments have aggressively enforced marijuana laws selectively against black people and communities, needlessly ensnaring hundreds of thousands of people in the criminal justice system at tremendous human and financial cost,” said ACLU Criminal Law Reform Project director Ezekiel Edwards in a statement accompanying the release of the report.

A report by one of ACLU’s state-level affiliates drives home just how selectively those laws are enforced in one of the country’s largest cities. A 2012 New York Civil Liberties Union report on NYPD’s “stop-and-frisk” policy found that, in 2011, New York cops stopped and frisked 168,126 black men between the ages of 14 and 24—despite the fact that only 158,406 young black men lived in the city at that time.

In other words: Over the course of a single year, the NYPD had stopped and frisked about 106% of the city’s young, black, male population.

The additional legal scrutiny placed on the black community has wide-ranging consequences beyond the criminal justice system. As sociologists Bruce Western and Becky Pettit wrote in their 2010 paper “Incarceration and Social Inequality” [PDF], the long-term social and economic disadvantages of doing time in prison are “invisible, cumulative, and intergenerational.” Just one example: For job-seekers, having a criminal record was “found to reduce callbacks from prospective employers by around 50%, and this effect was larger for blacks than whites.”

These results may help to explain why black/white wealth inequality has risen dramatically since the 1984. Selective policing of criminal drug laws disproportionately affects African-Americans (and especially black men), who are then placed at a great economic disadvantage for the rest of their lives. Their children then inherit that disadvantage.

A few states have reacted by relaxing their marijuana laws considerably. In November 2012, Washington and Colorado voters approved referendums which legalized recreational marijuana use. But federal law still prohibits marijuana usage, and the Justice Department has continued to crack down on marijuana dispensaries in places where they are legal under state law.