BBC Pop Up: Have Colorado's new gun laws failed?
In July 2012, a gunman shot dead 12 people and injured 58 more at a cinema in the Colorado town of Aurora.
James Holmes, who will face a murder trial in December, is accused of firing a shotgun and handgun during the screening of a Batman movie. He is also alleged to have used a semi-automatic rifle with a 100-round drum magazine.
The mass shooting, which was followed several months later by another at an elementary school in Newtown, Connecticut, prompted a national push for stricter gun control laws led by President Barack Obama.
In Colorado, which also endured the 1999 Columbine High School massacre, Democratic Governor John Hickenlooper signed laws banning the sale of ammunition magazines with more than 15 rounds and broadening the requirements for background checks before gun purchases.
Twenty months after that controversial laws went into effect, the magazine ban seems not to be working as intended. And in a western state where guns are said to be part of the way of life, the politicians who called for gun control are on the defensive.