Blacks are nearly four times more likely to be arrested for marijuana possession than whites – even though usage rates are comparable, according to a report issued today by the American Civil Liberties Union.

Marijuana enforcement has unfairly targeted black people, said the report, entitled “The War on Marijuana in Black and White.”

The racial disparity in marijuana arrests has markedly increased in the last 10 years, the ACLU found. Although black people are 3.7 times more likely to be arrested for possession than white people, blacks are now 30 times more likely to to be arrested for the drug in the counties with the widest disparities, they found.

The ACLU also analyzed the wider law enforcement handling of current marijuana laws. States spent an estimated $3.61 billion enforcing marijuana possession laws – in 2010 alone.

The current incarceration rate deprives record numbers of individuals of their liberty, disproportionately affects people of color, and has at best a minimal effect on public safety. Meanwhile, the crippling cost of imprisoning increasing numbers of Americans saddles government budgets with rising debt and exacerbates the current fiscal crisis confronting states across the nation.

Private prison companies, however, essentially admit that their business model depends on locking up more and more people. For example, in a 2010 Annual Report filed with the Securities and Exchange Commission, Corrections Corporation of America (CCA) stated: “The demand for our facilities and services could be adversely affected by . . . leniency in conviction or parole standards and sentencing practices . . . .” As incarceration rates skyrocket, the private prison industry expands at exponential rates, holding ever more people in its prisons and jails, and generating massive profits.