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Jeffrey D. Mamorsky is Co-Chair of the Labor & Employment Practice’s ERISA & Employee Benefits Litigation group. He concentrates his practice in the areas of compensation and employee benefits law. He has served as employee benefits counsel to large multinational corporations, financial institutions, insurance companies, closely held businesses, large not-for-profit organizations, governmental agencies, Big Four accounting firms, leading employee benefits consulting firms, large multiple employer plans and major multi-employer pension and welfare funds.


  • Virtually all aspects of employee benefits and compensation law
  • Creator of the Fiduciary Audit® Protection Program to assist plan sponsors avoid Internal Revenue Service (IRS) and ERISA liability
  • Creator of the Fiduciary Audit® Privileged Process Review to determine whether robust procedures are in place for the monitoring of plan investment options and “reasonableness” of service provider direct and indirect compensation and that those procedures are followed and documented. The Review provides a first line of defense for employers and plan fiduciaries in the event of ERISA "excessive fee" litigation alleging breach of fiduciary and prohibited transaction claims for lack of governance control and failure to monitor the reasonableness of fees 
  • Compliance with IRS' Employee Plans Compliance Resolution Program
  • Design and drafting of qualified and non-qualified employee benefits programs
  • Representation of plan fiduciaries in governmental and adversarial proceedings
  • Protection of plan fiduciaries from Employee Retirement Income Security Act (ERISA) and Internal Revenue Service (IRS) liability, including review and analysis of appropriate fiduciary and IRS liability insurance coverage
  • Protection of the tax-deferred retirement benefits of public sector employees with the Fiduciary Audit® Operational Compliance Program for Governmental Retirement Plans that helps governmental entities achieve IRS tax qualified status for their retirement plans and avoid immediate taxation of participant vested benefits
  • Employee benefit aspects of mergers and acquisitions
  • Welfare benefit plan documentation and compliance with all applicable laws
  • Evaluation of health care plan compliance with all applicable laws, including review of managed care and related service provider agreements
  • Employee benefit plan compliance with federal and state laws relating to employment discrimination
  • Analysis of retirement and health legislation and regulations



  • Development of the Fiduciary Audit® Operational Review System Technology which enables corporate plan sponsors, hospitals and other not-for-profit corporations, large multiple employer plans, and boards of trustees of multi-employer plans to establish best practice self-audit internal control procedures designed to assure operational compliance with ERISA and IRS qualification requirements and internal control procedure audit requirements on a cost-effective basis.
  • Development of the Fiduciary Audit® Protection Program which provides the opportunity for plan sponsor employers and board of trustees (in the case of a multi-employer plan) to be eligible for enhanced insurance protection covering IRS monetary sanctions and the cost of IRS-mandated benefit corrections.
  • Development of the Fiduciary Audit® Privileged Process Review which determines whether robust procedures are in place for the regular monitoring of plan investment options and “reasonableness” of service provider direct and indirect compensation and that those procedures are documented and followed.
  • Preparation of comprehensive annual evaluations of employee benefit plan operational compliance with ERISA and related IRS requirements for plan sponsors as well as development of fiduciary compliance programs for financial institutions, insurance companies, plan administrators and trustees.
  • ERISA counsel in "excessive fee" litigation case recovering $10 million in hidden fees for major multiple employer pension plan (Geraghty v. Vagley).
  • ERISA counsel in landmark case involving the concept of "partial termination" under Section 411 (d)(3) of the Internal Revenue Code which requires full and immediate vesting in the event of a substantial reduction in plan participation (Walsh v. A&P). The case for the first time established that a partial termination could occur over several years as the result of a significant corporate event.
  • ERISA counsel in landmark case on the valuation of a participant's accrued benefit in a defined benefit pension plan. (District 65 v. Harper & Row). The case led to legislation requiring qualified plans to state and limit the interest rate used in valuing benefits.
  • ERISA counsel in important decision of Second Circuit Court of Appeals which held that the New York State Superintendent of Insurance, who, acting as rehabilitator and liquidator of an insurance company under state court orders, terminated retirement benefits of former employees of an insurance company could not be considered a "fiduciary" within the meaning of ERISA (Levy v. Lewis).
  • Evaluation of Health Care Plan Compliance under ERISA and the Internal Revenue Code (IRC) through a Fiduciary Audit® Operational Review including review and/or negotiation of written health care plan documents under ERISA, insurance policies, third party administration agreements, analysis of ERISA fiduciary liabilities under such agreements, filing of required government forms for annual returns; qualification of voluntary employee beneficiary associations and cafeteria plans under the IRC and compliance with various rules under health care legislation and regulations (e.g., Consolidated Omnibus Budget Reconciliation Act (COBRA), Health Insurance Portability and Accountability Act (HIPAA) and Patient Protection and Affordable Care Act (PPACA).
  • Preparation of a cost-effective single plan document and summary plan description for all welfare benefit plans sponsored by an employer or trustees (in the case of a multiemployer plan) that incorporates whatever documentation the insurer or administrator provides, meets all compliance requirements under all applicable federal laws (ERISA, COBRA, IRC, Family and Medical Leave Act (FMLA), HIPAA, Uniformed Services Employment and Reemployment Rights Act (USERRA) and PPACA, etc.) and includes all required notices to employees and enrollment forms that are easily readable, user friendly and do not require annual review.

Recognition & Leadership

  • Listed, The Best Lawyers in America
    • Litigation - ERISA, 2005-2021
    • Employee Benefits - ERISA, 2005-2020
  • Listed, The Legal 500 United States, 2012-2022
    • Labor and Employment - Employee Benefits, Executive Compensation and Retirement Plans: Design, 2021-2022
    • Labor and Employment - ERISA Litigation, 2021
  • Listed, Benchmark Litigation, "Labor & Employment Star," 2019-2020
  • Listed, Super Lawyers magazine, New York Metro Super Lawyers, 2006-2009, 2014-2021
  • Team Member, a Law360 "Employment Practice Group of the Year," 2011, 2013
  • Listed, Madison Who's Who, 2007
  • Mr. Mamorsky's two-volume treatise Employee Benefits Law and the Employee Benefits Handbook have been cited as authority by the following federal and state courts:
    • U.S. Supreme Court: Hughes Aircraft Company v. Jacobsen, 525 U.S. 432, 438; 119 S. Ct. 755, 760
    • U.S. Supreme Court: Hazen Paper Company v. Biggins, 507U.S. 604, 609; 113 S.Ct. 1701, 1706
    • First Circuit Court of Appeals: National Education Association-Rhode Island v. Retirement Board of the Rhode Island Employees'' Retirement System, 172 F.3d 22, 160
    • First Circuit Court of Appeals: Gaskell v. The Harvard Cooperative Society, 3 F.3d 495, 497
    • Third Circuit Court of Appeals: Taylor v. The People's National Gas Company, 49 F.3d 982, 987
    • Third Circuit Court of Appeals: Barrowclaugh v. Kidder, Peabody & Co., Inc., 752 F.2d 923, 930
    • Seventh Circuit Court of Appeals: James v. UOP, 16 F.3d 141, 142
    • Seventh Circuit Court of Appeals: Health Cost Controls of Illinois, Inc. v. Washington, 187 F.3d 703
    • Ninth Circuit Court of Appeals: Dugan v. Hobbs, 99 F.3d 307, 311
    • Ninth Circuit Court of Appeals: Anrdt v. Security Bank S.S. B. Employees'' Pension Plan, 182 F.3d 538, 23
    • U.S. District Ct., D. Delaware: Flying Tiger Line v. Central States, Southeast and Southwest Areas Pension Fund, 704 F.Supp. 1277, 1283
    • U.S. District Ct., N.D. Illinois: Central States, Southeast and Southwest Areas Pension Fund v. Carstensen Freight Lines, Inc., 1997 WL 391928, 3
    • U.S. District Ct., E.D. Louisiana: LaFargue v. Jefferson Parish, LA., 1999 WL 997496
    • U.S. District Ct., D. New Jersey: Crausman v. Curtis-Wright Corporation, 676 F.Supp. 1302, 1303
    • U.S. District Ct., S.D. New York: Devito v. Pension Plan of Local 819 I.B.T. Pension Fund, 975 F.Supp. 258, 267
    • U.S. District Ct., E.D. Pennsylvania: McVeigh v. Philadelphia National Bank, 796 F.Supp. 173, 175
    • Court of Appeals of New York: Majauskas v. Majauskas, 61 N.Y. 2d 481, 490, 463 N.E. 2d 15, 20
    • N.Y. Supreme Court, Special Term, Nassau County: Young v. Sheet Metal Workers'' International Assoc. Production Workers Welfare Fund; 447 N.Y.S. 2d 798, 802
  • Charter Fellow, American College of Employee Benefits Counsel
  • Member, IRS Northeast Region Pension Liaison Group
  • Founding member and former Counsel, ERISA Industry Committee ("ERIC")
  • Citizen and Liveryman of City of London, United Kingdom
    • Granted Freedom of the City of London, May 2008
    • Invested as a Liveryman in the Worshipful Company of Wheelwrights, July 2008
    • Appointed as Court Assistant to the Worshipful Company of Wheelwrights, April 2011-July 2018
    • Invested as a Liveryman in the Worshipful Company of Coachmakers, March 2014


  • LL.M., Taxation, New York University School of Law
  • J.D., New York Law School
  • B.A., New York University
  • New York
  • Supreme Court of the United States
  • U.S. Tax Court
  • U.S. Court of Appeals for the Second Circuit
  • U.S. Court of Appeals for the District of Columbia Circuit
  • U.S. District Court for the Southern District of New York
  • U.S. District Court for the Eastern District of New York