Mark P. McGillis

Travis R. Mueller is a top attorney recognized by Best Lawyers in the practice area(s) of Corporate Law and Mergers and Acquisitions Law. Travis R., who practices law in Milwaukee, Wisconsin, has been recognized since 2022. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Travis R. is held by other top lawyers in the same geographic and legal practice area.

Gregory assists his clients with family law matters. He is recognized by judges and peers as one of Wisconsin’s premier family law attorneys. He uses his extensive skill, training, and experience to help his clients achieve successful resolutions of their divorce, paternity, custody, placement, and support matters. Gregory is a Fellow in the American Academy of Matrimonial Lawyers and a Board Certified Family Law Trial Advocate by the National Board of Trial Advocacy. He is uniquely pos...

Lee Anne Conta is a Shareholder in the Litigation and Risk Management Practice Group. She focuses her practice in insurance coverage and litigation and is co-Chair of the Insurance Coverage and Risk Management Section. She advises clients on a variety of insurance coverage issues nationwide, including coverage issues arising in commercial, intellectual property, construction, and environmental matters. Lee Anne has been involved in numerous cases at the appellate court levels, including prese...

Gregory A. Storm is a top attorney recognized by Best Lawyers in the practice area(s) of Employee Benefits (ERISA) Law. Gregory A., who practices law in Milwaukee, Wisconsin, has been recognized since 2016. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Gregory A. is held by other top lawyers in the same geographic and legal practice area.

John Sikora is a Shareholder representing clients in tax planning, tax controversies and the buying and selling of businesses and real estate with a particular focus on corporate, partnership and other business matters. John is an adjunct professor of law at Marquette University Law School, where he has taught the tax practice and procedure and corporate income tax courses. John has also taught the taxation of partnerships and S corporations course to graduate accounting degree candidates at ...

Sally Piefer is a top attorney recognized by Best Lawyers in the practice area(s) of Employment Law - Management and Labor Law - Management. Sally, who practices law in Milwaukee, Wisconsin, has been recognized since 2025. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Sally is held by other top lawyers in the same geographic and legal practice area.

Dave Roettgers is a Shareholder focusing his practice on the purchase and sale of businesses, taxation, corporate finance and business law. He is a Certified Public Accountant and uses his prior experience at Arthur Andersen LLP where he provided tax planning and business advice for individual and business clients. Representative Matters and Experience Representation of families and owners in all types of business planning including the transition of the business to the next generation, finan...

Larri J. Broomfield is a top attorney recognized by Best Lawyers in the practice area(s) of Corporate Law and Health Care Law. Larri J., who practices law in Milwaukee, Wisconsin, has been recognized since 2006. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Larri J. is held by other top lawyers in the same geographic and legal practice area.

Joe is the chair of the firm’s Litigation Practice Group. He manages a variety of complex cases involving software class actions, real estate, products liability, banking, intellectual property, and anti-trust matters. He has extensive experience representing both large and small plaintiffs and defendants in challenging civil litigation. He has been selected as a member of the Wisconsin Super Lawyers for six years in a row. Prior to joining O’Neil Cannon, Joe was an associate at t...

Background Mr. Prachthauser was born in Milwaukee, Wisconsin, on January 7, 1951. Prior to joining the firm, he was House Counsel for Employers Insurance of Wausau. He is married to Joan Marie, and they reside in Hartland, Wisconsin. He has two daughters, Emily and Tracy. Lectures Mr. Prachthauser is a frequent presenter and speaker for the State Bar of Wisconsin, American Board of Trial Advocates, and Wisconsin Academy of Trial Lawyers. He has been a Civil Trial Practice Instructor at the Un...