His rant covered a lot of ground. If you don't have time to watch the whole video, here's what he focused on:
The growing population of prisoners in the U.S.: America's prison population has been exploding since the war on drugs led to tough-on-crime laws being implemented in the 1980s and 1990s. The new mandatory minimums for even low-level drug offenses helped America's prison population grow to be the biggest in the world. As Oliver points out, the U.S. now has more prisoners than even China, whose population is four times that of the U.S.
Racism: Not only have America's harsh drug laws not solved the country's drug problem, but they also affect black people disproportionately. Oliver notes that despite the fact that black people use drugs at roughly the same rate as white people, black people are 10 times more likely to be imprisoned for drug offenses.
Solitary confinement: The practice of isolating a prisoner from human contact is a controversial one. Solitary confinement has been known to have serious mental and physical repercussions. Some prisoners report changes in vision, difficulty navigating surroundings, and prolonged depression. Inmates are often kept in 10 by 7 foot cells.
Sexual assault: Oliver points out that sexual assault is a big problem in America's prison system. In its most recent report on the issue, the Bureau of Justice Statistics said there were nearly 9,000 allegations of sexual victimization in prisons and jails in 2011 alone. As Oliver highlights in video clips from "Friends," Office Space," and even the kids show "SpongeBob SquarePants," this has become a running joke in America.
Food: Private contractors aiming to turn prison into a business have started providing food to some prisons. The goal is cutting costs, and it's led to prisons running out of food and finding maggots in meals, Oliver says.
Healthcare: These contractors have also taken over healthcare operations in some prisons across the country. Although prison healthcare costs have plummeted in some states as a result of this, Oliver says deaths have significantly increased and conditions have deteriorated to a remarkable extent. One inmate who had a C-section in jail told Al Jazeera America's "America Tonight" that doctors used sugar to treat her wounds.
Privatization: Allowing contractors to run entire prisons presents an even broader set of problems, according to Oliver. The companies might have a financial incentive to keep people incarcerated and run the prisons as leanly as possible, so pay and staffing levels plunge and conditions sometimes become inhumane. One private prison company lost its contract with a facility in Mississippi after investigators found that physical and sexual abuse was rampant in the facility.
Oliver also called out Americans for looking the other way and ignoring the pervasive problems.
"The rest of us are much happier completely ignoring it, perhaps because it's so easy not to care about prisoners," he said.