Dale O. Thornsjo

Dale O. Thornsjo


Dale Thornsjo focuses his Minnesota-based litigation practice on the continually evolving insurance coverage and liability issues raised construction, products liability, toxic tort and environmental matters. 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.

Mr. Thornsjo has also 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 and 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 Emeritus 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 legal services in the constantly morphing litigation and business environments.  Dale has taken on these roles 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 Legislature 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.




  • Prisk v. Travelers Indem. Co. of Am., __F.4th__, 2023 WL 5493752 (8th Cir. Aug. 25, 2023)
  • Wesser v. State Farm Fire & Cas. Co., 989 N.W.2d 294 (Minn.2023) (amicus)
  • St. Matthews Church of God & Christ v. State Farm Fire & Cas. Co., 981 N.W.2d. 760 ( Minn. 2022) (amicus)
  • Poitra v. Short, 966 N.W.2d 819 (Minn. 2021) (amicus)
  • King's Cove Marina, LLC v. Lambert Com. Constr. LLC,  958 N.W.2d 310 (Minn. 2021) (amicus)
  • Stand Up Multipositional Advantage MRI, P.A., v. Am. Family Ins. Co., 889 N.W.2d 543 (Minn. 2017) (amicus)
  • Poehler v. Cincinnati Ins. Co., 899 N.W.2d 135 (Minn. 2017) (amicus)
  • Wilbur v. State Farm Mut. Auto. Ins. Co., 892 N.W.2d 521 (Minn. 2017) (amicus)
  • Wilcox v. State Farm Fire and Cas. Co., 874 N.W.2d 780 (Minn. 2016) (amicus)
  • Schroeder v. Western Nat. Mut. Ins. Co., 865 N.W.2d 66 (Minn. 2015) (amicus)
  • Graphic Communications Local 1B Health and Welfare Fund “A” v. CVS Caremark Corp., 850 N.W.2d 682 (Minn. 2014) (amicus)
  • Engineering & Const. Innovations, Inc. v. L.H. Bolduc Co. Inc., 825 N.W.2d 695 (Minn. 2013) (amicus)
  • 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)
  • Independent School District 833 v. Bor-Son Constr., Inc., 631 N.W.2d 437 (Minn. Ct. App. 2001)
  • 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)
  • Frank v. Winter, 528 N.W.2d 910 (Minn. Ct. App. 1995)
  • 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)
  • Harder v. Austin Mut. Ins. Co., 481 N.W.2d 17 (Minn. 1992)
  • 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)
  • Austin Mut. Ins. Co. v. Templin, 435 N.W.2d 584 (Minn. Ct. App. 1989)