Douglas Tumminello, Lewis Roca Photo

Douglas B. Tumminello

Litigation Practice Group Leader, Partner
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Whichever direction a dispute may take, Doug provides careful, efficient, and value-conscious service to help clients meet their objectives and protect their businesses.

Doug Tumminello is a trial lawyer who represents companies in civil lawsuits ‎involving significant financial or reputational exposure, often involving crisis management. Doug's practice focuses on complex business, business tort, and intellectual property litigation, including class and mass actions. He represents a ‎variety of well-known business and nonprofit entities as litigation and ‎trial counsel and has tried cases in the state and federal courts of Colorado and Wyoming, as well as in ‎private arbitrations, and has argued before Colorado and federal ‎courts of appeal. Doug’s litigation experience includes injury for intentional wrongs and negligence (including claims for supervisory and vicarious liability), contracts, real estate, products liability, supply chain, intellectual property, waiver/exculpatory contracts, and insurance-related claims. He also regularly advises businesses concerning the formation, corporate governance and compliance, risk management, and strategic planning issues.

Doug is the practice group leader of the firm's Litigation Practice Group and serves as chair of the firm's Sports, Entertainment, and Recreation Industry Group. He is a well-regarded ‎national speaker and has given a number of keynote addresses to ‎business, civic and nonprofit organizations, schools, and churches. 

Personal Approach

Doug is attentive, experienced, highly proficient, and willing to take any matter to trial when necessary to achieve clients’ strategic goals, while at the same time very skilled and successful at delivering outcomes that maximize value through negotiated resolutions. Clients find his charming and witty sense of humor refreshing and enjoy working with him through the most challenging matters. His commitment to providing an outstanding customer experience is admired by clients and colleagues alike, and his long-term clients appreciate his responsiveness whether during office hours, in the evening, or over the weekend.

During his time as a cadet at West Point, Doug took a Constitutional law class and quickly became interested in pursuing a legal career. When away from his work, Doug is an extreme adventurer who has summited Mt. Everest ‎and set world records for rowing a rowboat 3,600 miles across the ‎Indian Ocean from Australia to Mauritius. He has engaged in numerous expeditions across the world’s polar regions, mountains, and oceans.

More About Douglas B. Tumminello


  • J.D., University of Denver, Sturm College of Law, Order of St. Ives, 1996
  • B.S., United States Military Academy, West Point, 1987

Bar Admissions

  • Colorado
  • Wyoming

Court Admissions

  • Colorado Court of Appeals
  • Colorado State Judicial District Courts
  • Colorado Supreme Court
  • U.S. Court of Appeals, Tenth Circuit
  • U.S. District Court, District of Colorado
  • U.S. District Court, District of Wyoming
  • U.S. Supreme Court
  • Wyoming State Courts
  • Wyoming Supreme Court


  • The Explorers Club, Member
  • Member, Rocky Mountain District Export Council
  • North Routt Community Charter School, Board member
  • Steamboat Christian Center, Board member
  • Denver, Northwestern Colorado, Colorado and American Bar Associations, Member
  • 14th Judicial District, Colorado, Judicial Performance Commission, Chair (former)
  • City of Steamboat Springs, Colorado, Parks and Recreation Commission (former)
  • Sherpa Memorial Foundation, Board of Directors and President (former)
  • Himalayan Rescue Association USA, Board of Directors (former)
  • Yampa Valley Gives, Board of Directors (former)
  • Military & Veterans Affairs Section Colorado Bar Association, Vice-Chair (former)

Representative Matters

  • Trial counsel in multimillion-dollar trial representing an electrical generation and transmission company in one of the nation’s first fully remote trials as a result of COVID restrictions on in-person trials.
  • Trial counsel for defendant in a federal court case seeking a multimillion-dollar award for alleged sexual assault. Prevailed following a jury trial.
  • Trial counsel for a national company in private arbitration over breach of contract and business tort claims. At arbitration, prevailed on all of the claims brought against his client, and on his client’s counterclaims against the plaintiff, which then resulted in a settlement favorable to his client.
  • Litigation and trial counsel for institutions facing claims for supervisory and managerial liability stemming from allegations of intentional wrongs.

  • Arbitration counsel for national youth sports camp company in litigation over sale of the company, resulting in favorable settlement prior to arbitration hearing.
  • Counsel for real estate investment trust over breach of contract related to sale of medical office complex. Case settled favorably the week prior to jury trial.
  • Counsel for a national real estate investment trust, defending claims of asbestos exposure at an apartment complex. Successfully defended the claims brought by over 150 plaintiffs, which the plaintiffs estimated to be in excess of $24 million, and obtained a complete summary judgment dismissal of all claims.
  • Litigation counsel for multiple schools and other organizations sued under the Colorado Child Sexual Abuse Accountability Act.
  • Litigation counsel for UFC champion and title holder over sponsorship/influencer agreements. 
  • Counsel for elite-level athlete over assault allegations. 

Honors & Recognitions

  • The Best Lawyers in America, Commercial Litigation, Product Liability Litigation - Defendants, 2020-2024
  • Colorado Super Lawyers, Business/Corporate, Business Litigation, 2019-2024
  • Litigation Counsel of America, Fellow




  • Presenter, "Experience Amplified – a Client Service Model," USLaw Network, February 2020
  • Presenter, "Combating Product Counterfeiters," Outdoor Industry Association (OIA) Webinar, January 2020
  • Presenter, "Understanding Product Liability Risks," Outdoor Industry Association (OIA) Webinar, September 2019
  • Co-presenter, "Solving the International Expansion Puzzle – Sustain Your Company’s Global Footprint and Expand Your Business Into Key Markets," Outdoor University, Outdoor Retailer Summer Market, June 2019
  • Co-presenter, "Service Metamorphosis – Driving Performance Improvements," Legal Marketing Association, March 2019
  • Co-presenter, "Intellectual Property Quiz Show," Outdoor University, Outdoor Retailer Summer Market, July 2017
  • Presenter, Keynote presentation, National State Auditors Association, June 15, 2016
  • Speaker, "Emerging Corporate Compliance Trends and Predictions," Association of Corporate Counsel, April 20, 2016
  • Presenter, "Intellectual Property, Manufacturing and Sales Warranties, and Liability Waivers in the Outdoor Manufacturing and Services Industry," Yampa Valley Entrepreneurship Center, March 25, 2016
  • Presenter, Keynote presentation, Medtronic, Inc. Sales Team, 2015
  • Presenter, Keynote presentation, IMA Financial Group, 2015
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