• Boston College, B.A. (1987) cum laude
  • Fordham University School of Law, J.D. (1990)


  • New York
  • U.S. District Court for the Southern District of New York
  • U.S. District Court for the Eastern District of New York

Brian J. O'Sullivan

Senior Counsel

Brian O'Sullivan is a senior counsel in Crowell & Moring's Insurance/Reinsurance practice group in the firm's New York office. Prior to joining the firm, Brian was a partner at other law firms in New York, where his practice focused principally on insurance and reinsurance dispute resolution.

Over the past twenty five years, Brian has represented insurance and reinsurance clients in negotiations, mediations, arbitrations and litigations involving both traditional and finite reinsurance, workers’ compensation carve-out reinsurance, property and casualty, life, accident and health insurance, as well as viaticals and life settlements. The issues involved in those matters include misrepresentation, non-disclosure, and rescission claims; complex issues of contract construction and underwriting intent, including number of occurrences, aggregate extension clauses and "event" language, the recoverability of expenses in addition to limits, DJ expenses and commutation payments, ECO, XPL, and annualization; late notice defenses; redomestications; privilege and access to records; pre-hearing security; broker liability; as well as all aspects of reinsurance arbitration and litigation procedure and practice.

Brian has also been actively involved in major  insurer restructurings and matters involving the rehabilitation and liquidation of domestic and foreign insurance and reinsurance companies.  He has also advised insurers, reinsurers and investors regarding reinsurance structures and contract wording issues relating to variable annuity products and reinsurance contract wording issues relating to insurance-linked securities


Admitted to practice: New York; U.S. District Courts for the Southern and Eastern Districts of New York

Representative Matters

Examples of Brian’s representations include:

  • representing ceding company in arbitration involving the recoverability of tens of millions of dollars under finite reinsurance agreement;
  • representing ceding companies and reinsurers in disputes concerning the allocation, aggregation and cession of asbestos, environmental and other claims;
  • representing workers compensation carriers and occupational accident reinsurers in arbitrations and litigations to collect hundreds of dollars from reinsurers/retrocessionaires alleging fraudulent inducement;
  • representing life insurer in arbitration to collect from reinsurer alleging fraud;
  • representing insurer in concurrent litigations with reinsurer on inwards and outwards contracts; and
  • representing insurers in coverage actions relating to asbestos and environmental claims.

Speeches & Presentations

  • "Issues to Consider When Dealing With Non-US counterparties," Re Contracts 2019 Conference: The Art of Designing Reinsurance Contracts and Programs, New York, NY (July 25, 2019). Speaker: Brian J. O'Sullivan.
  • "What a Headache: Mock Reinsurance Arbitration and Roundtable Concerning Sports-Related Head Injuries," AIRROC 2013 West Coast Insurance and Reinsurance Conference, Newport Beach, CA (September 19, 2013). Speakers: Michael K. Robles and Brian J. O'Sullivan.


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