Sean T. McAllister

Founder Attorney

Request for Sean to Speak at your Cannabis Event

Frequent topics:
– Pesticide Laws
– Regulatory Issues


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Sean T. McAllister is one of the nation’s leading marijuana lawyers and he is one of the only major marijuana lawyers licensed to practice law in both Colorado and California. Sean has twenty years experience working on marijuana law reform. He founded the non-profit Sensible Colorado that worked on all the ballot initiatives in Colorado that culminated in recreational legalization in 2012. Sean represented some of the first dispensaries to emerge in Colorado beginning in 2009 and he has built a reputation as an aggressive and pragmatic advocate for his clients.

Sean has litigated several groundbreaking marijuana cases in Colorado. Sean has sued regulators over enforcement actions, litigated pesticide standards for marijuana grows at the state and local level, and negotiated settlements for some of the most serious marijuana rules violations. He was co-counsel on the case suing the Colorado Department of Public Health and Environment in 2008 that overturned the original 5 patient limit. This lawsuit broke open the medical marijuana industry and led to the opening of dispensaries. He litigated a ban on medical marijuana dispensaries in Eagle, Colorado and authored a ballot initiative that ultimately led to the ban being overturned by a vote of the people. He has sued several cities and counties related to their implementation of the marijuana law on behalf of aggrieved clients.

In Sean’s role as corporate counsel to dispensaries, he handles all aspects of corporate formation, dissolution, governance, purchase agreements, promissory notes, civil litigation and land use matters. Sean has also represented several dispensary owners and employees charged or accused of criminal violations in state and federal court. In addition, he has pioneered complicated licensing agreements with celebrity personalities.

Currently, Sean is defending the nation’s first product liability action against a marijuana manufacturer.

Sean has been widely recognized by the legal marijuana industry, most recently receiving the following awards:

  • 5280 Magazine named Sean a “Top Marijuana Lawyer” in Colorado in 2016 and 2017
  • 2015 and 2013 MVP Award from the Cannabis Business Association for his work on the regulated marijuana industry.
  • 2009 Friend of Reform Award from Sensible Colorado for his efforts to legalize marijuana.

Sean frequently attends and participates as an expert speaker at various conferences for the legal marijuana industry. He has led sessions on many important topics such as:

  • Under the Microscope: State Oversight for Testing Labs, NCIA Cannabis Business Summit & Expo, Oakland, CA (June 2016).
  • Challenges &Opportunities of Owning & Operating a Marijuana Business, at the Colorado Marijuana Industry Legal and Accounting Advice and Compliance live CLE Seminar. (December 2015)
  • Organic Cannabis & Pesticide Uses, at the 4th Annual Marijuana Business Conference & Expo held in Las Vegas, Nevada. (November 2015)
  • Celebrity Endorsements: Legal Challenges & Opportunities, at the Cannabis Creative Conference held in Portland, Oregon. (July 2015)
  • Marijuana Real Estate- Roles and Responsibilities of Landlords, Tenants and Investors, at the National Cannabis Industry Association Cannabis Business Summit & Expo held in Denver, Colorado. (June 2015)
  • Regulatory Compliance in Marijuana Law, at the NORML Legal Seminar held in Aspen, Colorado. (May 2015)
  • Future Marijuana Legislation, at the High Times Cannabis Cup held in Denver, Colorado. (April 2015)
  • DUID-Marijuana Laws, at the Drug Policy Alliance conference held in Los Angeles, California. (October 2013)
  • Criminal Justice Issues and Marijuana, at the Students for Sensible Drug Policy Conference held in Denver, Colorado. (March 2012)
  • Legalization of Marijuana under Amendment 64, at the Lions and Rotary Club Presentations. (2012)
  • Numerous presentations on the rollout of marijuana legislation in Colorado, at the Cannabis Business Alliance marijuana forums held at Casselman’s in Denver, Colorado. (2011-2013)
  • Future of legalization at the Drug Policy Alliance conference held in Los Angeles, California. (November 2011)
  • Testimony in front of Colorado and Hawaiian legislatures of marijuana legislation. (2010-2014)
  • Marijuana legislation at the Denver 420 Rally. (2010-2012)
  • Regulatory Framework of Medical Marijuana at the CLE International “Medical Marijuana Conference” held in Denver, Colorado. (2010)

Sean has won several awards in the legal community within the city of Denver and state of Colorado:

  • 2007 Pro Bono Award for his work assisting victims of domestic violence.
  • 2008 Certificate of Appreciation from the People’s Law Project for his pro bono defense of protesters at the 2008 Democratic National Convention.
  • 2009 Gideon Award from Colorado Criminal Defense Bar for his dedication to the defense of the poor.

Sean is a life member of the NORML Legal Committee. From 2000 to 2003, Sean served as an Assistant Attorney General with the State of Colorado. Sean is a graduate of the University of Colorado School of Law, class of 1999.