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About John O. Brennan



After working as an associate for Kwiatkowski & Ryan from 1991 to 1998, John O. Brennan
partnered with John E. Ryan and founded Ryan & Brennan LLP. The firm became known as
Ryan, Brennan & Donnelly in 2003.


John focuses on litigation and has vast experience working as Defense-Counsel for institutional
clients including Allianz, Broadspire, CorVel, Everest National Insurance Company, Liberty
Mutual and United States Aircraft Insurance Group.


  • Boston College (B.A., 1987)​

  • St. John’s University (J.D., 1990)

Bar Admissions

  • Admitted to bar, 1991 New York

  • U.S. District Court, Eastern and Southern Districts of New York 1993

  • U.S. Court of Appeals, 2nd Circuit 2000


  • AV Peer Review Rated – Highest rating from Martindale–Hubbell, Inc.

  • Member: Nassau County and New York State Bar Associations

  • Other Affiliations: Prosecutor, Village of Stewart Manor, March 1998 - May 2009

  • Counsel, Zoning Board of Appeals of Village of Stewart Manor June 2002 – March 2009

  • Village Attorney, Village of Stewart Manor April 2004 – April 2009

  • Member: Board of Governors of St. John’s University October 2008 – July 2014

  • Member: Board of Trustees of St. John’s University July 2014 – May 2017

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