Philip Jacob Weiser (born May 10, 1968) is an American attorney and politician who has served as the attorney general of Colorado since 2019. He is the Hatfield professor of law and telecommunications, executive director and founder of the Silicon Flatirons Center for Law, Technology, and Entrepreneurship, and dean emeritus at the University of Colorado Law School.Professor Philip J. Weiser faculty profile. University of Colorado. Retrieved September 15, 2017. He previously served in the Obama and Clinton administrations in the White House and Justice Department. A member of the Democratic Party, he was elected Attorney General for the State of Colorado in the 2018 election, defeating Republican George Brauchler on November 6, 2018. He was re-elected in 2022.
On January 2, 2025, Weiser announced his candidacy in the 2026 Colorado gubernatorial election. He won the Democratic nomination on June 30, 2026, defeating U.S. Senator Michael Bennet in the primary.
Early life and education Weiser was born to an Ashkenazi Jewish family. His grandparents survived the Holocaust, and his mother, Estare, was born in the Buchenwald concentration camp in 1945.
After high school, Weiser studied political science at Swarthmore College, graduating in 1990 with a Bachelor of Arts with high honors. He then attended the New York University School of Law, where he was an Articles Editor for the New York University Law Review. He graduated from NYU Law in 1994 with a Juris Doctor degree and Order of the Coif honors.
Academic and federal government career
Law clerk and Clinton administration After graduating, Weiser served as law clerk to Judge David Ebel of the Tenth Circuit Court of Appeals from September 1994 to August 1995. He was then a law clerk to Justices Byron R. White and Ruth Bader Ginsburg in the U.S. Supreme Court from September 1995 to August 1996. Following his clerkships, he was senior counsel to Joel Klein, the Assistant Attorney General for the Justice Department's Antitrust Division from 1996 to 1998.
Academic career In 1999, Weiser joined the University of Colorado Law School in Boulder as a professor of law and telecommunications. There, Weiser established the national center of excellence in telecommunications and technology law and founded the Journal on Telecommunications & High Technology Law.Journal on Telecommunications and High Technology Law. jthtl.org. He also founded the Silicon Flatirons Center for Law, Technology, and Entrepreneurship and he wrote and taught in the areas of competition policy, innovation policy, and Internet policy.
From June 2011 through July 2016, Weiser served as the fifteenth dean of the law school, and he was named one of the National Jurist's most influential leaders in legal education. Through the Silicon Flatirons Center, Weiser developed a range of programs to build up CU Boulder's support for entrepreneurship and has linked it to the local startup community. Some of the initiatives include Tech Lawyer Accelerator, the Corporate Counsel Intensive Institute and the Daniels Fund Ethics Initiative.
Obama administration
In 2009, President Barack Obama appointed Weiser as Deputy Assistant Attorney General in the Justice Department's Antitrust Division. He took the post in July 2009, taking a leave of absence from the University of Colorado Law School. In 2010, President Obama named him senior advisor for technology and innovation to the National Economic Council Director, and he participated in a series of policy initiatives.
Attorney General of Colorado
Elections
Colorado Attorney General Election, 2018PartyCandidateVotes%DemocratPhil Weiser1,281,91651.6RepublicanGeorge Brauchler1,120,83445.1LibertarianWilliam Robinson81,2223.3 Weiser was elected Attorney General for the State of Colorado in the 2018 election, defeating Republican George Brauchler on November 6, 2018. Weiser took office in January 2019, becoming the first Democratic Colorado Attorney General in 15 years. Later that same month, Weiser withdrew Colorado from a lawsuit that his predecessor, Republican Cynthia Coffman, had filed against the Clean Power Plan.
In the 2022 Colorado Attorney General election, Weiser was re-elected for a second term, defeating Republican challenger John Kellner and winning over 54% of votes cast.
Tenure
Lawsuits against the Trump administration Since President Donald Trump took office in January 2025, Weiser has filed or joined more than 65 lawsuits challenging Trump administration policies. Weiser's lawsuits range in topics, but have been mostly focused on funding cuts, the environment, immigration, and federal firings. As of June 2026, the Colorado Sun continuously updated tracker reported that courts had partially or fully blocked the challenged policies in 36 cases, left them in place in 8 cases, and were still considering 22. At a February 2026 news conference, Weiser said that his federal litigation had restored or protected more than $1 billion in Colorado funding. The following cases, selected for their impact on Colorado and presented in chronological order, illustrate the range of Weiser's federal litigation.
On April 1, 2025, Weiser's office led a coalition of 25 states and territories in suing the U.S. Department of Health and Human Services over its abrupt termination of $11 billion in federal public health funding the previous week. The administration had justified the termination by declaring the COVID-19 pandemic over and the grants therefore "no longer necessary," although Congress had reauthorized the funding as recently as June 2023, after the formal end of the pandemic emergency. The complaint states that the affected funds supported infectious-disease tracking, immunization access, emergency preparedness, mental health and substance abuse services, and public health data infrastructure across the plaintiff states. In Colorado specifically, the terminations threatened the state's Behavioral Health Administration and 68 of its grantee partners, including the Mobile Crisis Response program and the Assertive Community Treatment program, which served more than 650 individuals with serious mental illness. The court granted a temporary restraining order within two days of filing, entered a preliminary injunction six weeks later requiring HHS to restore the funding, and saw the administration's appeal voluntarily dismissed shortly thereafter.
On October 28, 2025, Weiser joined attorneys general from 25 states in a lawsuit to prevent the Trump administration from suspending payments under the Supplemental Nutrition Assistance Program (SNAP). SNAP provides approximately $120 million in benefits to 600,000 Coloradans each month. USDA had taken the position that it lacked authority to use approximately $5 billion in SNAP contingency funds to cover November 2025 benefits during the ongoing federal government shutdown. On May 1, 2026, USDA reversed course and agreed not to withhold SNAP benefits. The parties then jointly asked the court to dismiss the case, which it did.
On January 9, 2026, Weiser joined attorneys general from California, Illinois, Minnesota, and New York in suing the Trump administration over a freeze of more than $10 billion in federal funding for child care, cash assistance, and social services programs across the five states. The administration had announced the freeze days earlier, citing concerns about fraud and benefits going to undocumented immigrants, although undocumented immigrants do not qualify for the Temporary Assistance for Needy Families (TANF) program or Colorado's child care assistance program under existing rules. The same day the suit was filed, the court granted a temporary restraining order requiring the administration to release the funds. A preliminary injunction followed in February 2026, blocking the administration from re-imposing the restrictions. The three programs at issue provide Colorado with approximately $300 million annually and support more than 27,000 children in the state's child care assistance program, more than 50,000 children through TANF-funded cash assistance, and another 14,400 children through prevention and intervention services.
On February 18, 2026, Weiser's office co-led a coalition of 13 state attorneys general, with California Attorney General Rob Bonta and Washington Attorney General Nick Brown, in filing suit opposing the Trump administration's termination of approximately $8 billion in clean-energy and infrastructure awards nationwide, including more than $600 million for Colorado projects affecting Colorado State University, the Colorado School of Mines, and the University of Colorado. The complaint alleged that the executive branch could not unilaterally cancel funding Congress had appropriated under the 2021 Bipartisan Infrastructure Law and the 2022 Inflation Reduction Act. The case remained pending as of mid-2026.
Opioid settlement In July 2019, Weiser amended Colorado's existing lawsuit against Purdue Pharma to name eight members of the Sackler family, which privately owned Purdue, along with several former company executives. The amended complaint alleges "fraudulent and reckless conduct" under three Colorado statutes: the Consumer Protection Act, the Organized Crime Control Act, and the Uniform Fraudulent Transfer Act. The complaint also alleges that warnings about addiction risk were brushed aside in pursuit of sales.
In total, the lawsuits Weiser filed and those he joined have brought more than $912 million to Colorado, including at least $32 million from an April 2026 settlement with the Albertsons grocery chain.
Tenant protections Weiser has made housing a major focus of his tenure, pursuing legal action against large rental property owners and managers accused of unfair trade practices.
In a joint action with the Federal Trade Commission, Weiser's office alleged what it called a "pattern of deceptive pricing" identified through a Consumer Protection Bureau investigation. According to the state, Greystar advertised attractive monthly rents while concealing additional mandatory recurring charges covering services such as pest control, trash removal, concierge services, utility management, and amenity access. The state alleged that prospective tenants could not discover the full cost of a unit until after signing a lease and paying non-refundable application fees.
Greystar settled with the state of Colorado for more than $1 million. According to the state's announcement, the funds would be used for "reimbursement of actual costs and attorneys' fees, future consumer protection or antitrust enforcement, consumer education, or public welfare purposes." Under the terms, Greystar must disclose the full monthly cost of leasing a unit, broken down by fee category, and may no longer require deposits before complete pricing has been disclosed to the tenant.
In a separate matter, Colorado joined the U.S. Department of Justice and seven other states in an antitrust suit against RealPage, the Texas-based company that dominates the market for landlord revenue-management software. Weiser's office later amended the complaint to add Greystar, LivCor, Camden Property Trust, Cushman & Wakefield, Willow Bridge, and Cortland as defendants, alleging the companies coordinated through RealPage's software to suppress competition on rental pricing. Greystar alone operates more than 45,000 rental units in Colorado.