Millions of people living in US territories currently don't have the full ability to vote — and John Oliver of Last Week Tonight is not happy about it.

"Voting rights in this country, much like John Travolta's hair, are still very much a work in progress," Oliver said. "There are the obvious obstacles for many Americans, such as increasingly restrictive voter ID laws, but there's also the less obvious ones."

Oliver was referring to US citizens in Puerto Rico, the US Virgin Islands, Guam, the Northern Marianas, and American Samoa who don't have full voting rights. More than 4 million people live in US territories, and more than 98 percent of them are racial minorities. None of them have full representation in the US government: they can't vote for president, and they don't have voting representatives in Congress.

What's the historical justification for this? Essentially, racism. The US Supreme Court in the early 20th century ruled that these territories are inhabited by "alien races" that may not be able to understand Anglo-Saxon principles that guide American law. Although this decision wasn't supposed to be permanent, governments as recent as the Obama administration have cited it to continue denying people in US territories equal rights.

"There are a lot of complicated issues surrounding what the precise status of all the US territories should be and what the people who live there would prefer," Oliver said. "But surely, when it comes to denying Americans the right to vote, we have to find a better reason than citing a 100-year-old legal decision written by a racist that was always supposed to be temporary."

Further reading: 6 questions about Washington, DC, statehood you were too disenfranchised to ask.