Grant C. Killoran

Milwaukee, WI Directions

Recognized in Best Lawyers since 2015

Awarded Practice Areas

Commercial Litigation Litigation - Health Care

Visit Website

414.276.5000

Awarded Practice Areas

Commercial Litigation Litigation - Health Care

Works at

O'Neil, Cannon, Hollman, DeJong & Laing SC

18 Best Lawyers awards

Biography

Grant Killoran is a shareholder at O’Neil Cannon and the past Chair of its Litigation Practice Group. He has significant and diverse trial experience representing clients in Wisconsin State and Federal Courts, and courts around the country, focusing on complex business, health care and employment law disputes. Grant also devotes a portion of his practice to arts and entertainment law, with an emphasis on the music industry.

Grant is listed in The Best Lawyers in America in the practice areas of Commercial Litigation and Litigation-Health Care. He has been named a Top 50 lawyer in Wisconsin and Top 25 lawyer in Milwaukee by Super Lawyers. He has an AV–Preeminent Peer Review Rating™ with Martindale-Hubbell, which “reflects an attorney who has reached the heights of professional excellence, has usually practiced law for many years and is recognized for the highest levels of skill and integrity.” He has a 10.0 out of 10.0 rating by Avvo, a national attorney rating service which uses a mathematical model to rate attorneys based on experience, professional achievements, industry recognition and professional conduct.

Grant is the Wisconsin State Delegate to the American Bar Association, a member of the ABA House of Delegates and a past member of the ABA’s Board of Governors. He is a Life Fellow of the American Bar Foundation and a Fellow of the Wisconsin Law Foundation. He is a Co-Chair of the American Bar Foundation for the State of Wisconsin.

Grant Assists Clients With

Complex Commercial and Business Litigation
Health Care Industry Litigation, Disputes and Contracting
Risk Management Counseling
Business Counseling and Advice
Restrictive Covenant and Trade Secrets Litigation
Corporate Disputes
Contract Disputes
Tort Disputes
Appellate Litigation
Alternative Dispute Resolution

Locations

Milwaukee, Wisconsin

414-276-5000

111 East Wisconsin Avenue, Suite 1400
Milwaukee, WI 53202

Education

University of Minnesota, J.D., graduated 1989

Affiliations

Delegate, American Bar Association House of Delegates (1997–2000, 2003– 2009, 2014–2020; 2021-present) - Delegate
Governor, American Bar Association (2021-present) (ABA Board of Governors’ Liaison to the ABA Section of Health Law, Commission on the American Jury, and Forum on Housing and Community Development Law) - Governor
American Bar Association House of Delegates - Delegate
American Bar Association Section of Litigation Health Law Litigation Committee (2007–2009) - Co-Chair
American Bar Association Section of Litigation Health Law Litigation Newsletter - Editor
American Bar Foundation - Fellow
American Health Lawyers Association - Member
Lex Mundi Health Care Industries Practice Group (2007–2009) - North American Regional Vice-Chair
Member, Meritas Health Care Industry Practice Group Steering Committee (2016-present) - Member
Meritas U.S./Canadian Litigation Group Steering Committee - Member
Milwaukee Bar Association Judicial Selection Committee (1997–2000, 2008–2011) - Member
Milwaukee Bar Association Milwaukee Justice Center Committee - Member
Wisconsin Law Foundation - Fellow

Client Testimonials

Awards & Focus

Recognized in The Best Lawyers in America^® 2026 for work in:

Commercial Litigation
Litigation - Health Care

Special Focus:

COVID-19

Awards:

Grant is listed in The Best Lawyers in America® in the practice area of Litigation–Health Care
Grant has a 10.0 out of 10.0 rating by Avvo, a national attorney rating service which uses a mathematical model to rate attorneys based on experience, professional achievements, industry recognition and professional conduct
Grant has been selected as an Outstanding Newsletter Editor and an Outstanding Subcommittee Chair by the American Bar Association
Grant has been named one of “Wisconsin’s Top Rated Lawyers” for health care law by “The Definitive Guide to Legal Representation in Wisconsin”
Law & Politics Magazine repeatedly has selected Grant for inclusion in Wisconsin Super Lawyers, a distinction limited to the top 5% of Wisconsin attorneys
Nightingale’s Health Care News, a national health law publication, has named Grant an “Outstanding Health Care Litigator”
The Milwaukee Young Lawyers Association has awarded Grant its Community Service Award
Grant was named to the “2015 Irish Legal 100” as a leading figure in law across the U.S. by The Irish Voice Newspaper
Grant is a Fellow with the American Bar Foundation, membership in which is limited to one-third of one percent of the lawyers in America
Grant is a Fellow with the Wisconsin Law Foundation, membership in which is limited to 2.5% of the members of the State Bar of Wisconsin
Grant has been selected as a “Top Rated Lawyer” in health care law by American Lawyer Media at Martindale-Hubbell®
Grant repeatedly has been named one of Milwaukee’s “Leading Lawyers” by M Magazine, in conjunction with Avvo, in the area of health care law and in litigation
Grant repeatedly has been elected by the State Bar of Wisconsin to serve as one of its five Delegates to the American Bar Association House of Delegates
Grant has an AV–Preeminent Peer Review Rating™ with Martindale-Hubbell®, which “reflects an attorney who has reached the heights of professional excellence, has usually practiced law for many years and is recognized for the highest levels of skill and int

Additional Information

Case History

Cases

Representative Case Experience

In the Matter of the Rehabilitation of the Segregated Account of Ambac Assurance Corporation, Dane County, WI, Case No. 10-CV-1576 (2017)
Walby v. BuySeasons, Inc., U.S.D.C. for the E.D. of WI Case No. 2:17-CV-896
Brown v. State Collection Service, Inc., et al., U.S.D.C. for the E.D. of WI Case No. 16-CV-1533
Lang v. Lang, et al., Milwaukee County, WI, Circuit Court Case No. 15-CV-7464
Myers v. Americollect, Inc., et al., U.S.D.C. for the E.D. of WI Case No. 1:15-CV-965 (2017)
Marine Travelift, Inc v. Cimolai Technology S.p.A., et al., U.S.D.C. for the E.D. of WI Case No. 1:16-CV-338 (2016)
Nowosad, et al. v. Synthes, Inc., et al., Milwaukee County, WI, Case No. 14-CV-8461 (2016)
Buckner v. Horizon Trust Co., et al., Milwaukee County, WI, Case No. 15-CV-9791 (2016)
Bellin Memorial Hospital, Inc. v. Bay Area Medical Center, Inc., Marinette County, WI, Case No. 14-CV-67 (2015)
ProHeath Care, Inc. v. HealthEOS by MultiPlan, Inc., Waukesha Court, WI Case No. 11-CV-1049 (2014)
Orbis Corporation v. Rehrig Pacific Company, U.S.D.C. for the E.D. of WI Case No. 2:12-CV-1073 (2013)
In the Matter of the Rehabilitation of the Segregated Account of Ambac Assurance Corporation, Dane County, WI, Case No. 10-CV-1576 (2012)
HarQen v. Fastaff, LLC, Milwaukee County, WI, Case No. 11-CV-3627 (2012)
Royal Concrete Concepts, Inc. v. Shuttlelift, Inc., U.S.D.C. for S.D. of FL Case No. 11-80821-CV (2011)
Fincantieri Group, LLC v. Marine Travelift, Inc., Door County, WI, Case No. 11-CV-59 (2011)
Jedson Engineering, Inc. v. Spirit Construction Services, Inc., et al., Brown County, WI, Case No. 07-CV-2545 (2011)
W.G.&R. Furniture Company v. Boston, Inc., et al. Brown County, WI, Case No. 09-CV-2385 (2010)
Specialty Tapes, LLC v. CAT Industries, LLC, et al., Racine County, WI, Case No. 09-CV-1698 (2010)
Mahoney v. Prevea Health Services, Inc., et al., Brown County, WI, Case No. 08-CV-1925 (2009)
Tanke v. Prevea Clinic, Inc., Brown County, WI, Case No. 08-CV-1433 (2009)
Laughlin, et al. v. ProHealth Care, Inc., et al., Waukesha County, WI, Case No. 05-CV-1109 (2007)
Covenant Medical Center, Inc. v. Skierka, et al., Butler County, IA, Case No. LACV 019544 (2007)

Representative Case Experience (Part 2)

Cedar Valley Lawn Care, Inc. v. Covenant Health System, Inc., Black Hawk County, IA, Case No. LACV 096464 (2007)
Summers v. Hurley Health Services, et al., Genesee County, MI, Case No. 05-81687 (2007)
The Cadle Company II, Inc. v. Bain, Brown County, WI, Case No. 05-CV-169 (2007)
Boruta v. Medical College of Wisconsin, Milwaukee County, WI, Case No. 06-CV-6794 (2006)
Rivera, et al. v. Network Health Plan of WI, U.S.D.C. for E.D. of WI Case No. 02-1055 (2005)
Fisher Scientific Company LLC v. Witte, et al., U.S.D.C. for W.D. of PA Case No. 04 0596 (2006)
Benitiec Australia Ltd. v. Promega Corporation, et al., U.S.D.C. for DE Case No. 04-889 (2005)
Godiwalla v. Children’s Hospital, Inc., et al., U.S.D.C. for E.D. of WI Case No. 02-C-906 (2004)
Cababa v. St. Francis Hospital, Inc., U.S.D.C. for E.D. of WI Case No. 02-C-673 (2003)
Lloyd v. Kenosha Hospital, Inc., U.S.D.C. for E.D. of WI Case No. 00-642 (2002)
St. Joseph Regional Medical Center v. General Growth, et al., Milwaukee County, WI, Case No. 00-CV-921 (2002)
Fuhrmann, et al. v. Network Health System, Inc., Waupaca County, WI, Case No. 00-CV-174 (2001)
Radiology Consultants, S.C., et al. v. Huberty, et al., Racine County, WI, Case No. 99-CV-1729 (2000)
Renaissance Faire Limited Partnership v. Flex Cable/Kirkof Group, et al., Milwaukee County, WI, Case No. 90-CV-714 (1995)
Soik, et al. v. Stokely, USA, Inc., 175 Wis. 2d 456, 498 N.W.2d 897 (1993)

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