Daniel J. O’Brien

Phone: (414) 271-3400
Fax: (414) 271-3841
E-mail: djo@hallingcayo.com

Areas of Practice:

Bar Admissions:

  • Wisconsin, 1986
  • U.S. District Court Eastern District of Wisconsin, 1986
  • U.S. Court of Appeals 7th Circuit, 1987

Dan’s practice concentrates on litigation and trial work, with an emphasis on insurance defense, commercial and coverage litigation, insurance fraud investigations and Plaintiff’s personal injury work. He has tried over seventy cases to juries, including automobile accident cases for defendants and plaintiffs, medical malpractice cases for plaintiffs and defendants and coverage questions for insurers and insured’s. Dan has represented and obtained recoveries for several minors in significant injury cases and has tried punitive damage cases to juries for plaintiffs and defendants as well.

Dan is actively involved in alternative dispute resolution and has represented clients in hundreds of mediations where he has helped them resolve matters without the expense and uncertainty of trial. Dan also represents clients in Arbitration hearings and represents businesses and professionals in transactional and non litigation of matters, including negotiating and drafting shareholder, member and non compete agreements, and the acquisition and development of new facilities appearing before governmental bodies at public hearings required for approval. Dan uses a trial lawyer’s eye to help his clients avoid future litigation, while addressing the matter at hand.

Dan was elected to serve two terms on the Wauwatosa School Board from 2001 to 2007, a district with a $65 million dollar budget, 7,000 students and over 800 employees. He has lectured at the Marquette University Dental School on the subject of professional liability and has likewise lectured and spoken at seminars on topics ranging from material misrepresentation and fraud in the insurance claims process to the recovery of diminished value of an automobile in third party cases.

Dan is a 1986 graduate of Marquette University Law School. He received his Undergraduate degree from the University of Wisconsin, Milwaukee in 1983. He is admitted to practice in Wisconsin, the United States District Court for the Eastern and Western Districts of Wisconsin, as well as before the Seventh Circuit Court of Appeals.


  • Marquette University Law School, Milwaukee, Wisconsin
  • University of Wisconsin-Milwaukee, 1983 B.A.

Classes/Seminars Taught:

  • Lecturer, Dental Jurisprudence, “How to Avoid Professional Liability Claims from a Plaintiff’s lawyers Perspective”, Marquette University Dental School
  • Lecturer, “Material Misrepresentation: What’s Fraud Got to Do with It?”, State Farm Heartland Regional SIU Conference
  • Lecturer, “Recovery for Diminished Value of an Automobile in Third Party Claims”, State Farm Mutual Automobile Insurance Company Regional Office, Wauwatosa, Wisconsin