On July 20, 2012, a mass shooting occurred inside of a Century 16 movie theater in Aurora, Colorado, during a midnight screening of the film The Dark Knight Rises. A gunman, dressed in tactical clothing, set off tear gas grenades and shot into the audience with multiple firearms. 12 people were killed and 70 others were injured, the largest number of casualties in a shooting in the United States. The sole assailant, James Eagan Holmes, was arrested in his car parked outside the cinema minutes later. It was the deadliest shooting in Colorado since the Columbine High School massacre in 1999. Prior to the shooting, Holmes rigged his apartment with homemade explosives, which were defused by a bomb squad one day after the shooting.

The shooting prompted an increase in security at movie theaters across the U.S. that were screening the same film, in fear of copycat crimes. The shooting also led to a spike in gun sales in Colorado, as well as political debates about gun control in the United States.

Holmes confessed to the shooting, but pleaded not guilty by reason of insanity. Arapahoe County prosecutors sought the death penalty for Holmes. The trial began on April 27, 2015. He was convicted of twenty-four counts of first-degree murder, 140 counts of attempted first-degree murder, and one count of possessing explosives on July 16, 2015. On August 7, 2015, he was sentenced to life in prison without the possibility of parole. On August 26, 2015, he was given 12 life sentences, one for every person he killed, and 3,318 years for the attempted murders of those he wounded, and for rigging his apartment with explosives.