Halling & Cayo, S.C.
Patrick T Oneill

Patrick T. O’Neill

(414) 271-3400
(414) 271-3841 (fax)
[email protected]

View Patrick O'Neill's profile on LinkedIn

Practice Areas

Patrick is a trial attorney with a practice focused on civil litigation, including securities, business, and real estate matters. He routinely represents clients in federal court, state court, and arbitration forums. Patrick’s engaging personality and common-sense approach to problem solving allow him to achieve quick and meaningful results for his clients.

Patrick earned his law degree at the University of Wisconsin. During law school, he worked for multiple non-profit and government legal agencies, including the Wisconsin Supreme Court and the Wisconsin State Public Defender. Patrick completed his undergraduate studies at Georgetown University in Washington, DC. Before returning to his native Wisconsin to pursue a legal career, he lived and worked in the Persian Gulf for several years, where he developed a global perspective that continues to inform his work.

When Patrick is not in the courtroom or office, he can be found spending time with family and friends, running along the shores of Lake Michigan, skiing and hiking in the mountains, experimenting with a new recipe in the kitchen, or reading a good book.


  • University of Wisconsin Law School, J.D.
  • Georgetown University, B.S.

Professional Affiliations

  • State Bar of Wisconsin
  • Milwaukee Bar Association
  • Eastern District of Wisconsin Bar Association
  • Milwaukee Young Lawyers Association
  • Georgetown University Alumni Association


  • Wisconsin
  • 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