International Society of Primerus Law Firms
Dale O. Thornsjo
Practice Areas:

Minneapolis Attorney
Dale O. Thornsjo

Phone: 952.831.6544


Languages: English


Dale Thornsjo focuses his litigation practice on the continually expanding and shifting insurance coverage and liability issues raised construction, products liability, toxic tort and environmental matters. He represents primary and excess/umbrella insurers in a wide variety of property damage, bodily injury, personal and advertising injury trigger, allocation, duty to defend, “bad faith,” and “coordination of coverage” actions. He also continues his long-established practice of defending clients in mass tort, multiple-plaintiff or individual plaintiff cases in such diverse areas as asbestos, mold and “wet” buildings, building products, food adulterants and other substances.

In addition to his practice in Minnesota, Mr. Thornsjo has represented insurers, manufacturers and other entities in jurisdictions such as Iowa, Michigan, New York, North Dakota, South Dakota and Wisconsin.  He is a 1984 cum laude graduate of the William Mitchell College of Law (now Mitchell Hamline School of Law). He is a member of the Defense Research Institute, its Insurance Law Committee, and that Committee’s Commercial General Liability Subcommittee. As a member of DRI’s local arm, the Minnesota Defense Lawyers Association, he was a founding co-chairman of MDLA’s Insurance Law Committee, a past chair of the MDLA’s Toxic Tort and Environmental Law Committee, and is a member of its Construction Law Committee.  He is also a member of the Federal Bar Association, and the Association of the Bar of the United States Court of Appeals for the Eighth Circuit.

The Firm is a member of the International Society of Primerus Law Firms where Dale serves as the Chair of the Primerus Defense Institute’s Executive Committee.  In addition, Dale co-chairs Primerus’ groundbreaking Resources Committee which is focused on identifying, integrating and implementing technology and legal process management principles into the Society’s 170 law firms and 3,000 lawyers to enhance Primerus’ small and medium-sized firm members’ ability to effectively deliver their legal services in constantly morphing litigation and business environments.  Dale has taken these roles on following his work on the Primerus Defense Institute’s Insurance Coverage and Bad Faith Committee where he served on its Executive Committee as a member and its Chair for several years.

Dale is a frequent lecturer and author on complex insurance coverage and product liability matters, and has testified before various committees of the Minnesota House of Representatives and the Minnesota Senate on insurance coverage and bad faith issues.  Mr. Thornsjo chairs the Firm’s Insurance Coverage Practice Group and the Toxic Tort Practice Group. He has been recognized by his peers for inclusion in Best Lawyers®The Best Lawyers in America© publication, and has been selected as an insurance coverage “Super Lawyer” for many years.


  • Minnesota State Court (1984)
  • Federal District Court, District of Minnesota (1984)
  • Eighth Circuit Court of Appeals (1987)
  • Federal District Court, Western District of Wisconsin (1991)
  • Federal District Court, Eastern District of Michigan (1994)
  • Federal District Court, Eastern District of Wisconsin (2008)
  • Federal District Court, District of North Dakota (2009)
  • Pro Hac Vice admissions in Federal Courts in the Eastern District of New York and the District of South Dakota, and in state courts in Michigan, Wisconsin, Iowa and South Dakota

Author & Speaker

  • Conflicts & Reservations: Legal & Ethical Considerations for the Duty to Defend, Primerus Defense Institute 2011 Insurance Coverage & Bad Faith Seminar, Atlanta, GA (September 2011)
  • The Examination Under Oath and Minnesota No-Fault Claims: Life Before and After Thompson v. Western National, Insurance Federation Of Minnesota Seminar (August 2011)
  • 2011 Legislative Update, MDLA Insurance Law Committee Meeting (July 2011)
  • The “Good,” The “Bad,” and The “Ugly”: Treasure in Minnesota’s Bad Faith Law, MDLA’s 2010 Insurance Institute (October 2010)
  • 2009 Legislative Update, MDLA Insurance Law Committee Meeting (March 2009)
  • Reservations and Conflicts: Ethical and Legal Issues When Coverage is in Question, MDLA 44th Annual Mid-Winter Conference (February 2009)
  • The A.P.I. Case: The “Kiss O’ Death” of Kissoondath?, Minnesota Defense (Winter 2008)
  • Construction Defect Coverage Issues: Assessing Beachhead Defenses, 2008 MDLA Insurance Institute (Co-Chair) (November 2008)
  • Deal or No Deal?: The Reality of Insurance Settlements, MDLA 43rd Annual Mid-Winter Conference (February 2008)
  • Contractual Risk Management Through Insurance; MDLA’s 2007 Insurance Law Institute Co-Chair
  • Railroad Contractor and Outsource Liability Coverage: Practical Considerations When Addressing Indemnification and Additional Insured Issues (2006)
  • “Insuring” the Railroad’s General Liability Risks (2005)
  • Environmental Issues for Schools: Mold, Lead, Toxic Building Sites, and Other Unmentionables
  • Defense Considerations in Mold Litigation: Investigation, Causation, Mitigation & Remediation, Minnesota Defense (Fall 2002 and Winter 2003)
  • Insurance Settlements: “Reality Sliced and Diced”, Techniques in Mediation, Arbitration and Settlement, Minnesota Institute of Legal Education (2002)
  • Mold: The Litigation Blossoms, An Advanced Course, Minnesota Defense Lawyers Association Seminar, Co-Chair (2002)
  • Construction Considerations in Toxic Mold Litigation: Investigation, Causation, Mitigation & Remediation, ACI Conferences in Miami, San Francisco, New York, Miami (Co-Chair), and Toronto (2001 and 2002)
  • Subrogation: The Insurer Strikes Back, or, “We Can’t be Left Holding the Bag, So It Has to Be . . . .”, ACI Conferences in Miami, San Francisco and New York (2001 and 2002)
  • Winning Strategies for Litigating a Toxic Mold Case: A Multi-Perspective Roundtable (For the Defense), ACI Conference, San Diego (2001)
  • Construction Litigation Defects: Defense and Coverage Considerations in Construction Mold Cases
  • Insurance Coverage in Light of the New AIA Form A201
  • Minnesota Landfill Cleanup Act: Ready or Not, Here It Comes: State’s Rights Under Minnesota’s Landfill Cleanup Act, Minnesota Defense Lawyers Association Seminar (1998)
  • Commercial General Liability Policies: Environmental Claims
  • Minnesota Considerations for Environmental Insurance Coverage Claims
  • Dropdown Issues in Excess Liability Policies
  • Personal Injury and Advertising Injury Issues Raised in Commercial General Liability Policies
  • Midwest Environmental Claims Association Annual Bodily Injury Law Update

Reported Cases

  • Western Nat’l. Ins. Co. v. Thompson, 797 N.W.2d 201 (Minn. 2011) (amicus)
  • Cargill, Inc. v. Ace Am. Ins. Co., 784 N.W.2d 341 (Minn. 2010)
  • Star Windshield Repair, Inc. v. Western Nat’l Ins. Co., 768 N.W.2d 346 (Minn. 2009) (amicus)
  • Timmer v. Shamineau Adventures, 2007 WL 1121573 (Minn. App. 2007), Review Denied (Minn. June 27, 2007)
  • In Re: Silicone Implant Ins. Coverage Litigation, 652 N.W.2d 46 (Minn. App. 2002), aff’d in part and reversed in part, 667 N.W.2d 405 (Minn. 2003), reh’g denied (Minn. Sept. 29, 2003)
  • Continental Cas. Co. v. Auto-Owners Ins. Co., 238 F.3d 941 (8th Cir. 2000)
  • Ceridian Corp. v. SCSC Corp., 38 F.Supp. 1113 (D. Minn. 1999), aff’d, 212 F.3d 398 (8th Cir. 2000)
  • Dow Corning v. Continental Casualty, 1999 WL 33435067 (Mich.App.1999)
  • Hydrite Chem. Co. v. Aetna Cas. & Sur. Co., 220 Wis.2d 26, 582 N.W.2d 423 (Ct. App. 1998)
  • State v. Hydrite Chem. Co., 220 Wis.2d 51, 592 N.W.2d 411 (Ct. App. 1998)
  • Westling Mfg. Co., Inc. v. Western Nat. Mut. Ins. Co., 581 N.W.2d 39 (Minn. App. 1998)
  • Aetna Cas. & Sur. Co. v. Dow Chemical Co., 44 F.Supp.2d 847 (E.D. Mich. 1997), 933 F.Supp.2d 675 (E.D. Mich. 1996), 883 F.Supp.2d 1101 (E.D. Mich. 1995)
  • SCSC Corp. v. Allied Mut. Ins. Co., 536 N.W.2d 305 (Minn. 1995)
  • Sylvester Bros. Development Co. v. Great Cent. Ins. Co., 503 N.W.2d 793 (Minn. App. 1993), 480 N.W.2d 368 (Minn. App. 1992)
  • Holmes v. Watson-Forsberg Co., 488 N.W.2d 473 (Minn. 1992)
  • Souder v. Owens-Corning Fiberglas Corp., 939 F.2d 647 (8th Cir. 1991)

Contact This Firm

O'Meara, Leer, Wagner & Kohl, P.A.

7401 Metro Boulevard
Suite 600
Minneapolis, MN 55439-3034
United States

Law Firm Contact: Dale O. Thornsjo

Tel: 952.831.6544

Fax: 952.831.1869



Member Since: 2006

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