Gregory W. Lyons - O'Neil Cannon

Strength Through Tenacity

Greg represents clients in the prosecution and defense of complex commercial litigation. His extensive experience in commercial litigation has prepared him to successfully represent large corporations as well as small businesses and individuals.

Greg also has extensive experience representing individuals in inheritance litigation. He has successfully litigated many will contests and trust disputes throughout Wisconsin. Greg has accomplished tremendous results on behalf of trustees, personal representatives, and power of attorneys in large complicated disputes.

Greg has appeared in state and federal courts in numerous jurisdictions including California, New York, Texas, Arizona, Oregon, Florida, Illinois, and Washington D.C. Greg is a member of the Wisconsin state and federal courts, Seventh Circuit Court of Appeals, and the United States Supreme Court. Greg also serves as the Chairperson of the firm’s Ethics Committee.

Greg Assists Clients With

Inheritance Litigation
Will Contests
Trust and Estate Litigation
Complex Litigation
Commercial Litigation
Personal Injury
Products Liability Litigation
Insurance Coverage Litigation
Class Action Litigation
General Business Counseling
Contract Disputes
Tort Disputes
Appellate Practice

Professional Associations and Affiliations

Life Fellow, American Bar Foundation
State Bar of Wisconsin
Eastern District of Wisconsin Bar Association
Milwaukee Bar Association
Waukesha County Bar Associaton
Ozaukee Bar Association
Waukesha County Business Alliance
Defense Research Institute
Independent Business Association of Wisconsin

Court Admissions

Wisconsin
U.S. District Court, Eastern District of Wisconsin
U.S. District Court, Western District of Wisconsin
U.S. Court of Appeals, Seventh Circuit
U.S. Supreme Court
Various other state and federal courts across the U.S. on a pro hac vice basis

Awards/Distinctions

- Named 2022 Best Lawyers® “Lawyer of the Year” for Litigation–Insurance
- Named 2022 Attorney of the Year by Top 100 Registry
- Martindale-Hubbell® Peer Review Rating™–AV Preeminent, reflecting an attorney who has reached the height of professional excellence and is recognized for the highest levels of skill and integrity
- Selected for inclusion in The Best Lawyers in America®–Commercial Litigation in 2014 and Commercial Litigation and Litigation–Insurance in 2015–2024
- Selected as a Member of The Nation’s Top One Percent by the National Association of Distinguished Counsel, whose rosters “Consists of the leading legends of the legal profession”
- Fellow with the American Bar Foundation, membership in which is limited to one-third of one percent of the lawyers in America
- For more than 15 years, Law and Politics and Milwaukee Magazine has selected Greg for inclusion in Wisconsin Super Lawyers, a distinction limited to the top 5% of Wisconsin attorneys.
- Named one of “Milwaukee’s Leading Lawyers,” in 2015, 2016, and 2017 by M Magazine in Litigation. Only 2–5% of the top ranked attorneys published by Avvo for each category were recognized

Articles/Presentations

Speaker, Milwaukee Chapter of the Society of Financial Service Professionals, “Dealing with Possible Elder Financial Abuse and its Potential Legal Ramifications” (Milwaukee, WI, March 2020)
Author, “Wisconsin Supreme Court Determines Statutory Medical Malpractice Cap Constitutional” Meritas Healthcare Newsletter (January 2020)
Speaker, O’Neil, Cannon, Hollman, DeJong and Laing, “Deposition Preparation-Tips on How to Prepare a Non-Expert Witness for Deposition” (Milwaukee, WI, September 2017)
Speaker, O’Neil, Cannon, Hollman, DeJong and Laing Hot Legal Topics for Small Firms and Solo Practitioners seminar, “Commercial Arbitration: Arbitration in the United States and Abroad” (Milwaukee, WI, October 2015)
Speaker, O’Neil, Cannon, Hollman, DeJong and Laing, Hot Ethics Topics for In-House Counsel seminar, “E-Discovery: The New Wisconsin Rules of Civil Procedure and Some Ethical Considerations for Managing Electronically Stored Information” (Milwaukee, WI, December 2010)
Speaker, State Bar of Wisconsin and Corporate Practice Institute, Inc., “Legal Ethics: A Review and Update, Including Emerging Issues” (Milwaukee, WI, December 2010)

Community Involvement

Board of Directors–Executive Committee, Secretary, Revitalize Milwaukee
Milwaukee Justice Center, Pro Bono Volunteer
Marquette University Law School, Former Member Alumni Association Board of Directors
University of Wisconsin–Whitewater, Former Member Dean’s Advisory Board
University of Wisconsin–Whitewater, Former Protégé–Mentor Program
Various school and church committees

In The News