John Oliver returned to Last Week Tonight with another examination of an unjust cog in America's criminal justice system: the unrepresentative makeup of trial juries. Serving on a jury of your peers" is an "essential civic duty", Oliver said. But in practice, said "peers" are not chosen from a fair cross-section of society. People of color and particularly black Americans are chronically underrepresented in jury pools. First, there's the list of potential jurors, which in many states draws from voter registration data or drivers' license lists, both of which disproportionately exclude people of color. Many states contract jury selection to private companies, whose methods, when revealed, fall far short of truly representative or random; Oliver pointed to one example in Tulsa, Oklahoma, where a private company accidentally excluded zip codes in which 90% of the county's black residents lived. Once potential jurors show up for selection, prosecutors can weed out jurors of color. Although the supreme court ruled in 1986 that prosecutors can't strike jurors on the basis of race, "it turns out that's a pretty easy rule to get around," said Oliver. "All you have to do is just come up with some reason other than race to strike a juror." To demonstrate the brazen efforts prosecutors will take to whitewash juries, Oliver pointed to the six murder trials for Curtis Flowers in Mississippi, a black man whose case eventually reached the supreme court, which decided that the prosecutor had repeatedly and blatantly filtered out any potential black jurors.