New permitting requirements for certain semiautomatic firearms in Colorado have sparked opposition from rural county sheriffs and the National Rifle Association since taking effect on August 1.

Senate Bill 25-003 mandates that buyers of specified semiautomatic rifles, shotguns, and some gas-operated handguns with detachable magazines first obtain an eligibility card from their county sheriff's office. The process includes a name-based background check, submission of government-issued photo identification, payment of fees, and review by the sheriff before applicants can complete a state firearms safety course and written exam administered by Colorado Parks and Wildlife. Approved cards remain valid for five years.

Several rural sheriffs have declined to participate in issuing the cards. Montezuma County Sheriff Steven Nowlin announced that his office would not manage or issue the required training certificates, citing insufficient funding and staffing to handle the added workload along with constitutional concerns. Other sheriffs in rural areas have issued similar statements of non-participation or limited their involvement to local residents only.

The National Rifle Association joined an ongoing lawsuit against the law, filed as Del Toro v. Polis by the Colorado State Shooting Association and individual plaintiffs. The suit challenges the permitting scheme as an unconstitutional burden that grants sheriffs discretionary power to deny applications based on predictions of future behavior.

Implementation has encountered delays and confusion in multiple counties, with some sheriff's offices reporting they were not prepared to process applications immediately upon the August 1 effective date. Urban and suburban offices in areas such as Denver and surrounding counties have generally complied with the requirements despite stated opposition from some officials.

The legislation, signed into law in April 2025, applies only to new purchases or transfers of covered firearms and does not affect previously owned weapons. Critics of the measure argue that it imposes unnecessary administrative hurdles on law-abiding residents without addressing criminal misuse of firearms.