Colorado is at the center of a sprawling legal fight with the federal government, and the disputes over guns, artificial intelligence, and sanctuary laws sit at the heart of it. As of mid-2026, the U.S. Department of Justice has sued the state or its largest city over immigration cooperation, a large-capacity magazine ban, and Denver’s assault weapons ordinance; Elon Musk’s xAI, joined by the DOJ, has sued to block the Colorado Artificial Intelligence Act; and Colorado has filed its own suit against the Trump administration over the relocation of U.S. Space Command. Most of these cases are unresolved. The sanctuary suit was dismissed and is now on appeal, enforcement of the AI Act has been paused, and the firearms cases are in their earliest stages.
Sanctuary Laws: Dismissed, Now on Appeal
The DOJ sued Colorado and Denver on May 2, 2025, arguing that four state laws and two Denver measures limiting cooperation with Immigration and Customs Enforcement were preempted by federal immigration law under the Supremacy Clause. The challenged laws barred local officers from detaining people solely on civil immigration detainers, restricted sharing personal information with federal immigration agents, and prohibited state and local governments from entering immigration detention agreements. An amended complaint in July 2025 added SB25-276 to the list.1Civil Rights Litigation Clearinghouse. United States v. State of Colorado The government said sanctuary policies had “tied the hands of law enforcement, emboldened dangerous criminals and left Colorado’s communities vulnerable.”2Courthouse News Service. US Sues to Kill Colorado Sanctuary Laws Protecting Immigrants
On March 31, 2026, U.S. District Judge Gordon P. Gallagher dismissed the case with prejudice. In a 13-page opinion resting on the Tenth Amendment’s anti-commandeering doctrine, he wrote that while the Constitution bars states from obstructing federal immigration enforcement, it does not force them to help. “Plaintiff seeks to usurp control over Colorado and Denver officials by dictating what the officials can and cannot do,” Gallagher wrote. “The Federal Government does not have the power to direct the Colorado legislature or Colorado state and local officials in such a fashion.”3Colorado Politics. Federal Judge Dismisses U.S. Government Lawsuit Against Colorado, Denver’s Sanctuary Laws Attorney General Phil Weiser called the ruling a “win for public safety.”4Courthouse News Service. Judge Rejects Trump Challenge to Colorado Sanctuary Laws
The DOJ filed a notice of appeal in late May 2026, sending the case to the Tenth Circuit.5Law360. Feds Appealing Loss in Colorado Sanctuary Suit A motion for attorneys’ fees filed by local defendants in April 2026 is still pending.1Civil Rights Litigation Clearinghouse. United States v. State of Colorado Separately, El Paso and Douglas counties sued Colorado and Governor Jared Polis in state court in April 2024, asking a Denver judge to overturn two of the same immigration laws so county sheriffs could cooperate with ICE.6Courthouse News Service. Two Conservative Colorado Counties Sue State so Sheriffs Can Send Undocumented Immigrants to ICE
xAI’s Challenge to the Colorado Artificial Intelligence Act
On April 9, 2026, xAI filed suit in the U.S. District Court for the District of Colorado to block enforcement of Senate Bill 24-205, the Colorado Artificial Intelligence Act. The case, xAI LLC v. Weiser (No. 1:26-cv-01515), names Attorney General Phil Weiser as defendant and is before Chief Judge Daniel D. Domenico.7Civil Rights Litigation Clearinghouse. xAI v. Weiser
Signed on May 17, 2024, the AI Act requires developers and deployers of “high-risk” AI systems to exercise reasonable care to prevent algorithmic discrimination in consequential decisions involving employment, housing, lending, health care, and education. Violations are treated as unfair trade practices carrying penalties up to $20,000, enforced exclusively by the Attorney General.8National Association of Attorneys General. A Deep Dive Into Colorado’s Artificial Intelligence Act Developers must document bias risks, notify deployers and the Attorney General when discrimination is found, and keep public disclosures. Deployers must run annual impact assessments, notify consumers before AI is used in consequential decisions, and give explanations and appeal rights when a decision goes against the person.9Center for Democracy & Technology. FAQ on Colorado’s Consumer Artificial Intelligence Act
xAI pressed four constitutional objections. The company argued the law violates the First Amendment by compelling it to “redesign Grok to reflect Colorado’s views on fairness and equity,” asserting that training AI models is protected expression. It invoked the dormant Commerce Clause, saying compliance would force nationwide product changes that outweigh any local benefit. It raised a due process vagueness claim, arguing that terms like “algorithmic discrimination” and “reasonable care” give no fair notice. And it challenged the law’s carveout for AI systems designed to increase diversity or redress historical discrimination as “codified discrimination” that violates equal protection.10Norton Rose Fulbright. xAI Sues, DOJ Intervenes, Enforcement of Colorado AI Act Suspended
DOJ Intervention and an Enforcement Pause
On April 24, 2026, the DOJ moved to intervene on xAI’s side, and the court granted the unopposed motion. The government’s complaint focuses on equal protection, arguing the law unconstitutionally requires AI companies to prevent unintentional disparate impact while exempting algorithms that advance diversity. Assistant Attorney General Harmeet K. Dhillon said the law coerces innovators into producing products that “advance a radical, far left worldview at odds with the Constitution.”11U.S. Department of Justice. Justice Department Intervenes in xAI Lawsuit Challenging Colorado’s Algorithmic Discrimination
Three days later, on April 27, 2026, Magistrate Judge Cyrus Y. Chung granted a joint motion by xAI and the Attorney General to suspend enforcement. Under the order, the state may not initiate enforcement or investigations under SB24-205 until 14 days after the court rules on xAI’s forthcoming preliminary injunction motion, which is due within 28 days after the Colorado General Assembly concludes its 2026 session and any related rulemaking is finalized. Other case deadlines are stayed in the meantime.12CourtListener. xAI LLC v. Weiser Docket The court has not reached the merits.10Norton Rose Fulbright. xAI Sues, DOJ Intervenes, Enforcement of Colorado AI Act Suspended
Firearms Suits: Denver’s Ordinance and the Magazine Ban
The DOJ opened two gun-law fronts in Colorado within 24 hours in early May 2026.
On May 5, 2026, the government sued Denver over a 1989 ordinance that bans possession of many semiautomatic weapons, including AR-15-style rifles, arguing the ordinance violates the Second Amendment under District of Columbia v. Heller, which protects weapons in “common use for lawful purposes.”13U.S. Department of Justice. Justice Department Sues City of Denver for Unconstitutional Weapons Bans Denver City Attorney Miko Brown had rejected the DOJ’s pre-suit demand to stop enforcing the ordinance and sign a consent decree, calling the federal action “baseless” and “a clear overreach.” Brown cited post-Bruen rulings from six federal appellate courts upholding similar bans, and argued that the federal statute the DOJ invoked, 34 U.S.C. § 12601, was designed for police-misconduct cases rather than facial challenges to local gun ordinances.14City and County of Denver. Denver Response to DOJ Notice of Suit
The next day, May 6, 2026, the DOJ filed United States v. Colorado (No. 1:26-cv-01950), challenging the state’s 2013 law restricting magazines capable of holding more than 15 rounds.15Bloomberg Law. DOJ Sues Colorado Over State Ban on Large-Capacity Magazines That law, passed after the 2012 Aurora theater shooting, was upheld by the Colorado Supreme Court in 2020. The DOJ again relied on Heller, arguing the restricted magazines come standard with commonly owned firearms. Weiser pledged to “vigorously defend” the law.16Colorado Newsline. Trump Administration Sues Colorado Over Large-Capacity Magazine Ban Neither firearms case has produced any rulings.
A Second Gun Suit, From the Other Side
A separate challenge is coming from gun-rights advocates. The Colorado State Shooting Association announced in June 2026 that it would file a federal lawsuit against HB26-1126, a new law Governor Polis signed on June 2, 2026, that expands government access to firearm purchase records. The group argues the law lets the Colorado Department of Revenue demand records from gun stores without a warrant, probable cause, or a stated reason, violating the Fourth Amendment.17KDVR. Colorado Gun Rights Group Files Federal Lawsuit Over Firearm Records Law The association is seeking an injunction while the case proceeds.18Sentinel Colorado. Colorado Gun Group to Sue Over New Firearm Purchase Record Law
The ICE Subpoena and the Scott Moss Case
In April 2025, ICE issued an administrative subpoena to the Colorado Department of Labor and Employment seeking personal information on 35 custodians of unaccompanied minor children. ICE said the data was needed to investigate possible human trafficking but offered no evidence supporting that claim.19Colorado Politics. Denver Judge Denies Gov. Polis Request to Dismiss ICE-Related Records Case
Scott Moss, then director of the Division of Labor Standards and Statistics, sued in June 2025 to stop the governor from complying, arguing it would violate state laws limiting information-sharing with ICE outside criminal investigations. Denver District Judge A. Bruce Jones granted a temporary injunction, and ICE has never moved to enforce the subpoena in court.19Colorado Politics. Denver Judge Denies Gov. Polis Request to Dismiss ICE-Related Records Case
Polis initially tried to comply, then reversed in early 2026 and asked the court to permanently block the release and dismiss the case. In April 2026, Judge Jones rejected that request, calling it “untethered to any rule of procedure.” When a second ICE subpoena arrived describing the request as part of an “ongoing criminal case,” the judge found it was likely an updated version of the first, using a “talismanic phrase” about criminal investigation to work around state law. He again barred the governor from directing state officials to comply. Polis’s attorneys filed a notice of appeal to the Colorado Court of Appeals in late May 2026. By early June 2026, the state had spent more than $215,000 on the litigation.20Denver Post. Colorado Jared Polis ICE Subpoena
Voter Registration Data
In December 2025, the DOJ sued Colorado Secretary of State Jena Griswold to compel release of unredacted voter registration records, including full names, dates of birth, residential addresses, and driver’s license or partial Social Security numbers. The case, United States of America v. Griswold (No. 25-cv-03967), was filed December 11, 2025, after Griswold formally refused the request on December 2.21Colorado Secretary of State. DOJ Voter Data Lawsuit Press Release The DOJ claims the refusal violates Title III of the Civil Rights Act of 1960 and says the data is needed for investigations under the National Voter Registration Act and the Help America Vote Act.22Democracy Docket. Colorado DOJ Voter Data Access Challenge Griswold moved to dismiss on February 10, 2026, and the ACLU of Colorado and the Colorado Alliance for Retired Americans intervened on the defense side.23ACLU of Colorado. United States of America v. Jena Griswold As of mid-June 2026, no ruling on dismissal has issued.24Civil Rights Litigation Clearinghouse. United States v. Griswold
Colorado’s Own Suit: Space Command
Colorado has also gone on offense. In October 2025, Weiser sued over the Trump administration’s decision to move U.S. Space Command headquarters from Colorado Springs to Huntsville, Alabama. The suit names President Trump, Defense Secretary Pete Hegseth, and other officials, arguing the move violates a federal law requiring congressional notice before relocating a major military headquarters and that Trump “openly admitted” the move was meant to punish Colorado for its mail-in voting system.25Federal News Network. Colorado’s Attorney General Sues Trump Administration Over Space Command Relocation
In January 2026, Weiser amended the complaint to add other federal actions he described as a “widespread campaign of retribution” against the state, including the termination of transportation funding, the closure of the National Center for Atmospheric Research, new eligibility requirements for federal food assistance, and the denial of FEMA relief after wildfires and floods.26Colorado Newsline. Lawsuit: Space Command Targeting Colorado The suit faces unusual opposition at home: the Colorado Springs City Council and El Paso County both passed resolutions against it, and the Colorado Springs Chamber of Commerce called the litigation “performative.”27KKTV. Colorado Springs Leaders Share Update on Space Command Litigation The Pentagon has continued the relocation process, standing up a task force to manage the move to Alabama.28Payload Space. Colorado Springs Opposes Lawsuit to Keep Space Command HQ
Where Things Stand
Weiser has framed the Attorney General’s office as defending the state against what he calls a “lawless, bullying administration” and has set up a complaint process for Colorado residents to report misconduct by federal agents.29Colorado Attorney General. Colorado Attorney General Homepage The administration argues Colorado’s laws obstruct federal authority on immigration, undermine constitutional rights on firearms and AI, and leave the state’s residents less safe. The sanctuary case is now before the Tenth Circuit. Enforcement of the AI Act is on hold. The two firearms suits are in their opening stages. The voter data dispute is awaiting a ruling on dismissal. The Space Command case is still pending. None of the central questions is close to settled.