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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.


  • 111 East Wisconsin Avenue, Suite 1400
    Milwaukee, WI 53202


  • English

Bar Admissions

  • Wisconsin, State Bar of Wisconsin


  • American Bar Foundation - Life Fellow
  • Defense Research Institute - Member
  • Eastern District of Wisconsin Bar Association - Member
  • Independent Business Association of Wisconsin - Member
  • Marquette University Law School - Alumni Association Board of Directors
  • Milwaukee Bar Association - Member
  • Milwaukee Justice Center - Pro Bono Volunteer
  • Ozaukee Bar Association - Member
  • State Bar of Wisconsin - Member
  • University of Wisconsin - Former Protégé–Mentor Program
  • University of Wisconsin–Whitewater - Former Dean’s Advisory Board
  • Waukesha County Bar Associaton - Member
  • Waukesha County Business Alliance - Member

Court Admissions

  • 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

Lawyer of the Year Badge - 2022 - Litigation - Insurance

Named "Lawyer of the Year" by Best Lawyers® for:

  • Litigation - Insurance, Milwaukee (2022)

Recognized in The Best Lawyers in America® 2023 for work in:

  • Commercial Litigation
  • Litigation - Insurance

Special Focus

  • COVID-19
  • Product Liability


  • Fellow with the American Bar Foundation, membership in which is limited to one-third of one percent of the lawyers in America
  • Named one of “Milwaukee’s Leading Lawyers,” of 2015 by M Magazine in Litigation. Only 2-5% of the top ranked attorneys published by Avvo for each category were recognized
  • 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” in 2015, 2016, and 2017
  • 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
  • For more than 10 years, Law & Politics and Milwaukee Magazine has selected Greg for inclusion in Wisconsin Super Lawyers, a distinction limited to the top 5% of Wisconsin attorneys.
  • Selected for inclusion in The Best Lawyers in America®–Commercial Litigation in 2014 and Commercial Litigation and Litigation–Insurance in 2015–2021


  • U.S. District Court, Eastern District of Wisconsin
  • U.S. District Court, Western District of Wisconsin
  • U.S. District Court, Northern District of Illinois
  • 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


  • 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)
  • Co-Author “What Happens if My Business Can’t Perform Its Contract Due to the Coronavirus?,” website article (March 19, 2020)
  • Author, "A Trustee’s Duty of Loyalty in Wisconsin," website article (July 31, 2018)
  • Author, "Mental Capacity Issues in Estate Planning Litigation," website article (March 30, 2018)
  • Speaker, O’Neil, Cannon, Hollman, DeJong & Laing, “Deposition Preparation-Tips on How to Prepare a Non-Expert Witness for Deposition” (Milwaukee, WI, September 2017)
  • Speaker, O’Neil, Cannon, Hollman, DeJong & Laing Hot Legal Topics for Small Firms & Solo Practitioners seminar, “Commercial Arbitration: Arbitration in the United States and Abroad” (Milwaukee, WI, October 2015)
  • Speaker, O’Neil, Cannon, Hollman, DeJong & 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)
  • Greg’s other seminar presentations include “Alter-Ego Doctrine” and “Piercing the Corporate Veil”

Community Service

  • Board Member, Revitalize Milwaukee
  • 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
  • Milwaukee Justice Center, Pro Bono Volunteer
  • Various church and school committees

Greg Assists Clients With

  • Will Contests
  • Inheritance Litigation
  • Trust & 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

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