Phil Weiser is a Democratic politician who has served as Attorney General of Colorado since 2019. His office is the designated enforcement authority for the Colorado AI Act (SB 24-205), and he is the named defendant, in his official capacity, in xAI v. Colorado.
Role: Attorney General of Colorado (2019–present) Party: Democratic
Background
Before entering elected office, Weiser was a technology-law professor at the University of Colorado Law School and a senior official at the U.S. Department of Justice (antitrust, Obama administration). He has served as Colorado's Attorney General since 2019, and his office has taken an active role in shaping and enforcing the Colorado AI Act (SB 24-205), a state-level general-purpose AI law.
Enforcement authority for the Colorado AI Act
The Colorado AI Act designates the Attorney General as the exclusive enforcement authority; there is no private right of action. Weiser's office is therefore the sole regulator empowered to investigate and bring actions against developers and deployers of "high-risk" AI systems for violations of the Act's bias, disclosure, and risk-management requirements. His office has issued interpretive guidance and participated in the statutory revision process ahead of the Act's effective date.
SB 26-189 repealed and reenacted Part 17 in May 2026 and preserved the attorney-general-only enforcement design, adding a 60-day right to cure that sunsets January 1, 2030 and annual reporting by the office from January 2028 (Colorado SB 26-189 (Signed Act, May 14 2026)). The office's rulemaking and supervisory functions under the reenacted Part 17, including the proposed 4 CCR 904-6 rules filed August 11, 2026, are covered at Colorado Attorney General (Colorado Department of Law).
xAI v. Colorado
Weiser is the named defendant, in his official capacity, in xAI v. Colorado, a First Amendment challenge brought by xAI against the Colorado AI Act. The complaint argues that the Act's obligations on AI developers violate the First Amendment and are preempted by federal law. The case is one of the early constitutional challenges to a state AI law and concerns the limits of state-level AI regulation. See also AI and the First Amendment.
Consumer-protection AI posture
Weiser has been active on AI-related consumer protection, including bias in algorithmic decisions (employment, insurance, housing), deepfakes targeting elections, and deceptive AI-generated content. He has publicly characterized Colorado's approach as "guardrails that permit innovation" rather than preemption-by-federal-inaction.
Sources
Relationships
- related: Colorado AI Act (SB 24-205) and SB 25B-004 (Date Amendment) — exclusive enforcement authority.
- related: Colorado Attorney General (Colorado Department of Law) — the office and department he heads, and its Part 17 rulemaking.
- contradicts: xAI LLC v. Weiser — Complaint (D. Colo. 1:26-cv-01515) — named defendant in xAI's First Amendment challenge.
- related: AI and the First Amendment — Weiser's enforcement posture is being tested constitutionally.
- instance-of: Techno-Federalism: How Regulatory Fragmentation Shapes the U.S.-China AI Race — state-level AI enforcement in the absence of federal preemption.