At least 3,728 prisoners in the United States will spend the rest of their lives in prison for non-violent offenses according to an American Civil Liberties Union (ACLU) study published on Wednesday.

The study, “A Living Death,” features key statistics about these prisoners, an analysis of the laws that produced their sentences, and case studies of 110 men and women serving these sentences. Of the 3,278 prisoners, 79 percent were convicted of nonviolent, drug-related crimes such as possession or distribution, and 20 percent of nonviolent property crimes like theft.

Also revealed was a stark racial disparity: The ACLU estimates that, of the 3,278 serving life without parole for nonviolent offenses, 65 percent are Black, 18 percent are white, and 16 percent are Latino, evidence of extreme racial disparities. Of the 3,278, most were sentenced under mandatory sentencing policies, including mandatory minimums and habitual offender laws that required them to be incarcerated until they die.

Blacks, for example, make up 13 percent of the U.S. population but comprise roughly 45 percent of the state and federal prison population, according to statistics from the U.S. Department of Justice.

A few particularly shocking cases of disproportionate sentencing are featured, including that of Stephanie Yvette George, who was convicted for unknowingly storing crack cocaine in her attic.

The drugs belonged to the father of one of George’s children who was hiding them in a lockbox at George’s house. Because George had previously been convicted of minor drug offenses -- never serving time in jail -- Judge Roger Vinson had no choice but to sentence her to life without parole.

“Your role has basically been as a girlfriend, bag holder and money holder,” Judge Vinson said at the sentencing hearing. “So certainly, in my judgment, it doesn’t warrant a life sentence. If there was some way I could give you something less than life I sure would do it, but I can’t,” he added.

"The punishments these people received are grotesquely out of proportion to the crimes they committed," said Jennifer Turner, ACLU human rights researcher and author of the report. "In a humane society, we can hold people accountable for drug and property crimes without throwing away the key."

Responding to increasing criticism, Attorney General Eric Holder announced in August that the Justice Department would attempt to ease America’s overcrowded federal prisons by reducing mandatory drug sentences -- a move that was cheered by liberals and conservatives who favor a reduction in federal prison spending.

Douglas Ray Dunkins Jr., who has served 22 years so far, told the ACLU, “It’s devastating, horrible, not being around to see [my children] graduate and go to school.” Dicky Joe Jackson, who has served 17 years, said, "I would rather have had a death sentence than a life sentence."

"The people profiled in our report are an extreme example of the millions of lives ruined by the persistent ratcheting up of our sentencing laws over the last forty years," said Vanita Gupta, deputy legal director of the ACLU. "We must change our sentencing practices to make our justice system smart, fair, and humane. It's time to undo the damage wrought by four decades of the War on Drugs and 'tough-on-crime' attitudes."

The federal courts account for 63 percent of the 3,278 life-without-parole sentences for nonviolent offenses. The remaining prisoners are in Louisiana (429 prisoners), Florida (270), Alabama (244), Mississippi (93), South Carolina (88), Oklahoma (49), Georgia (20), Illinois (10), and Missouri (1). The ACLU estimates that federal and state taxpayers spend $1.8 billion keeping these people in prison for life instead of more appropriate terms.

The United States has the largest incarceration rate in the world -- nearly 25 percent of the global inmate population -- despite having only 5 percent of the world’s population. In 2011 alone, there were 1.5 million drug arrests in the U.S., according to FBI statistics. More than 80 percent of those arrests were for drug possession.

Harsh sentencing guidelines are also proving to be costly to American taxpayers: the ACLU estimates the costs of keeping these prisoners in jail until they die -- instead of more appropriate terms -- at about $1.8 billion.