Philip Jacob Weiser (born May 10, 1968) is an American lawyer 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. 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.
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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. 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
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
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's 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 alleged 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.
2026 Colorado gubernatorial campaign
On January 2, 2025, Weiser announced his candidacy to replace term-limited Colorado Governor Jared Polis in the 2026 Colorado gubernatorial election. Weiser's campaign began 2026 with approximately $3.5 million and raised $822,000 in the first quarter of 2026. Significant donors included Merle Chambers and Pat Meyers. Weiser's campaign savings surpassed Bennet's to start 2026, but Rocky Mountain Way, a Super PAC supporting Bennet, made the total funds for each candidate similar.
At the Colorado Democratic Party's State Assembly on March 28, 2026, Weiser won 90% of the delegate vote, and appeared at the top of the ballot for the Colorado Democratic primary on June 30th.
On June 30, 2026, Weiser won the Colorado Democratic gubernatorial primary with 56.7% of the vote, beating U.S. Senator Michael Bennet.
Personal life
In 2002, Weiser married Heidi Wald, a physician, in Philadelphia, Pennsylvania, and they now live together with their two children in Denver.
Selected publications
Books
Phil Weiser & Jon Nuechterlein, Digital Crossroads: American Telecommunications Policy in the Internet Age (MIT Press 2013) ISBN 9780262519601.
Phil Weiser, Stuart Benjamin, Howard Shelanski & James Speta, Telecommunications Law and Policy (Carolina Academic Press 2012) ISBN 978-1-61163-691-8.
Phil Weiser, The Jury and Democracy: How Jury Deliberation Promotes Civic Engagement and Political Participation (Oxford University Press 2010) ISBN 0195377311.
Articles
Weiser, Philip J. (2001). "Federal Common Law, Cooperative Federalism, and the Enforcement of the Telecom Act". N.Y.U. L. Rev. 76 (6): 1692. Retrieved September 14, 2017.
Weiser, Philip J. (2003). "Cooperative Federalism and Its Challenges". Mich. St. L. Rev. 2003: 727. Retrieved September 15, 2017.
Weiser, Philip J. (2003). "Justice White and Judicial Review". U. Colo. L. Rev. 74: 1305. Retrieved September 14, 2017.
Weiser, Philip J. (2003). "Regulatory Challenges and Models of Regulation" (PDF). J. On Telecomm. And High Tech. L. 2: 1. Retrieved September 15, 2017.
Weiser, Philip J. (2003). "Toward A Next Generation Regulatory Regime" (PDF). Loyola L. Rev. 35: 41. Retrieved September 15, 2017.
Weiser, Philip J. (2005). "First Principles for an Effective Rewrite of the Telecommunications Act of 1996". AEI-Brookings Joint Center Paper Series. SSRN 707124.
Weiser, Philip J.; Hatfield, Dale N. (2005). "Policing the Spectrum Commons". Fordham L. Rev. 75 (2): 74. Retrieved September 15, 2017.
Weiser, Philip J. (2005). "The Ghost of Telecommunications Past". Mich. L. Rev. 103 (6): 1671. Retrieved September 14, 2017.
Weiser, Philip J. (2005). "The Relationship of Antitrust and Regulation in A Deregulatory Era". Antitrust Bulletin. 50 (September 2005). SSRN 814945.
Weiser, Philip J. (2010). "What Carrier Doesn't Address" (PDF). Ala. L. Rev. 61 (3): 571. Retrieved September 14, 2017.