Bill O'Brien is a founding partner of his Firm, Miller O'Brien Cummins. For 30 years he has practiced exclusively in the areas of workplace and employment rights, civil rights, and labor law. His client-focused practice entails constant strategic positioning, counseling, negotiation, arbitration and litigation on behalf of his clients. Bill has litigated, arbitrated and mediated hundreds of cases, obtaining substantial relief for his clients in single and multiple Plaintiff cases, as well as in class and collective actions.

Bill is among the first lawyers in Minnesota to be certified as a Labor/Employment Law Specialist. In 2006, Bill was admitted as a Fellow to the College of Labor and Employment Lawyers, a national professional association of leading labor and employment lawyers. Election as a Fellow is the highest recognition by one's colleagues of sustained outstanding performance in the profession, exemplifying integrity, dedication, and excellence. In 2011, Bill was chosen as the winner of the Karla Wahl Dedicated Advocacy Award, given annually by the Minnesota Chapter of the National Employment Lawyers' Association.

Since 2001 Bill has been identified as among the Best Lawyers in America. He has been designated a Minnesota Super Lawyer in every year such designations have been made. He has secured the highest rating, AV Preeminent, from the Martindale Hubbell lawyer rating service. U.S. News, along with Chambers USA, have ranked Bill's firm as among the nation's best employment law firms.

Bill is the former Chair of the Labor and Employment Section of the Mn Bar Association and former President of the National Employment Lawyers' Association, Mn Chapter. He received his J.D. from Northwestern University Law School, and a B.A. from Colgate University.