Sullivan
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Biography

Warren is a Partner in the Real Estate Department. Although his practice encompasses the entire range of commercial real estate law, he concentrates in the area of leasing.

Education
  • Boston University School of Law (J.D.)
  • University of Michigan (B.A.)
Bar & Court Admissions
  • Massachusetts
Professional Qualifications
  • Boston Bar Association
  • Chairman, Boston Bar Association Committee on Leasing, 1993-1995
Awards & Honors
  • Best Lawyers in America® (2013-2026)
  • Massachusetts Super Lawyers (2004, 2008, 2010-2014)
Community Engagement
  • Member, Town of Weston Finance Committee
44 Sullivan & Worcester Lawyers Named as “Best Lawyers” Award Recipients
Boston MA – Sullivan & Worcester today announced that 44 lawyers were recognized in the 2026 edition of Best Lawyers in America®. Three Sullivan partners also earned the 2026 “Lawyer of the Year” recognition from The Best Lawyers in America®. 39 of the firm’s lawyers in Boston, New York and Washington, D.C. were named as “Best Lawyers in America®,” and five Sullivan lawyers were recognized as “Ones to Watch” in the U.S. Lawyers of the Year David Nagle, managing partner of Sullivan, Amy Sheridan, and Lewis Segall were selected as "Lawyer of the Year" in Boston for Litigation and Controversy – Tax, Employee Benefits (ERISA) Law, and Mergers and Acquisitions Law, respectively. Only one lawyer is recognized as a "Lawyer of the Year" in each practice area and geographic location. These individuals are notable for receiving significantly higher ratings in Best Lawyers’ rigorous assessment process among the thousands of leading lawyers peer-reviewed in their markets. Best Lawyers in America® The firm’s 2026 Best Lawyers in Boston include Victor Baltera (Real Estate Law); Howard Berkenblit (Corporate Governance Law, Corporate Law); Harvey Bines (Corporate Compliance Law, Corporate Governance Law); Ashley Brooks (Real Estate Law); Joel Carpenter (Tax Law); Henry Comstock Jr. (Trusts and Estates); Christopher Curtis (Tax Law); Patrick Dinardo (Bankruptcy and Creditor Debtor Rights / Insolvency and Reorganization Law, Litigation – Bankruptcy); John Graham (Nonprofit / Charities Law, Tax Law); Ira Gross (Commercial Litigation); David Guadagnoli (Employee Benefits (ERISA) Law, Tax Law); Warren Heilbronner (Real Estate Law); Zachary Hyde (Patent Law); Richard Jones (Tax Law); Karen Kepler (Real Estate Law), Caroline Kupiec (Tax Law); Thomas Meyers (Patent Law); Lisa Mingolla (Trusts and Estates); Louis Monti (Real Estate Law); Cornelius Murray III (Trusts and Estates); David Nagle (Litigation and Controversy – Tax, Tax Law); Nicholas O'Donnell (Commercial Litigation); Ameek Ashok Ponda (Tax Law); Gregory Sampson (Environmental Law, Land Use and Zoning Law, Real Estate Law); Lewis Segall (Mergers and Acquisitions Law); Amy Sheridan (Employee Benefits (ERISA) Law); Laura Steinberg (Commercial Litigation); Sarah Wellings (Tax Law) and Amy Zuccarello (Bankruptcy and Creditor Debtor Rights / Insolvency and Reorganization Law, Litigation – Bankruptcy). Sullivan’s 2026 Best Lawyers in Washington, D.C. include John Chilton (Mutual Funds); Cameron Cosby (Tax); Nicole Crum (Mutual Funds); David Leahy (Mutual Funds); David Mahaffey (Mutual Funds & Securities Regulation); and Stephanie Monaco (Corporate, Mutual Funds, Private Funds / Hedge Funds, & Securities Regulation). The firm’s 2026 honorees in New York include Carole Bass (Trusts and Estates); J. Truman Bidwell, Jr. (Corporate); Domenick Pugliese (Mutual Funds); and Constantine Ralli (Trusts and Estates). Best Lawyers: Ones to Watch Awardees Best Lawyers awards this recognition to attorneys who are earlier in their careers for their outstanding professional excellence in private practice in the United States. Sullivan’s five lawyers earning this award include Alexander Gansebom (Corporate Governance and Compliance Law, Corporate Law, Health Care Law, Mergers and Acquisitions Law, Real Estate Law); Emily Goldschmidt (Corporate Law); Ryan Rosenblatt (Commercial Litigation); Ashley Tan (Real Estate Law); and Eric Victorson (Securities / Capital Markets Law). Best Lawyers Selection Methodology Recognition by Best Lawyers in America® is based on a peer review process designed to capture the consensus opinion of leading lawyers about the professional abilities of their colleagues within the same geographical and legal practice areas. About Sullivan Sullivan & Worcester (Sullivan) is a global, mid-sized law firm with lawyers in Boston, London, New York, Tel Aviv and Washington, D.C. Sullivan’s clients, including Fortune 500 companies, leading financial services firms and asset managers, boards of directors, real estate companies, and emerging businesses, rely on Sullivan’s ability to navigate complex legal and operational landscapes, the impeccable judgment of its lawyers, and its commitment to best‑in‑class client service.
33 Sullivan & Worcester Lawyers Recognized as Best Lawyers® Award Recipients
Boston, MA – Sullivan & Worcester announced today that 33 lawyers have been included in the 2025 edition of The Best Lawyers in America® and nine lawyers have been included in the 2025 edition of Best Lawyers: Ones to Watch®in America. Since it was first published in 1983, Best Lawyers has become universally regarded as the definitive guide to legal excellence. Best Lawyers has earned the respect of the profession, the media and the public as the most reliable, unbiased source of legal referrals. Its first international list was published in 2006 and since then has grown to provide lists in more than 75 countries. Lawyers on The Best Lawyers in America list are divided by geographic region and practice areas. They are reviewed by their peers based on professional expertise and undergo an authentication process to make sure they are in current practice and in good standing. Best Lawyers: Ones to Watch in America recognizes lawyers who are earlier in their careers for their outstanding professional excellence in private practice in the United States. The Sullivan attorneys listed as 2025 Best Lawyers in America®are: Victor Baltera – Real Estate Law Carole Bass – Trusts and Estates Howard Berkenblit – Corporate Governance Law; Corporate Law J. Truman Bidwell – Corporate Law Harvey Bines – Corporate Compliance Law; Corporate Governance Law; Corporate Law Ashley Brooks – Real Estate Law Joel Carpenter – Tax Law John Chilton – Mutual Funds Law Henry Comstock, Jr. – Trusts and Estates Nicole Crum – Mutual Funds Law Christopher Curtis – Tax Law Patrick Dinardo – Bankruptcy and Creditor Debtor Rights/Insolvency and Reorganization Law; Litigation/Bankruptcy John Graham – Non-Profit/Charities Law, Tax Law Ira Gross – Commercial Litigation David Guadagnoli – Employee Benefits (ERISA) Law; Tax Law Warren Heilbronner – Real Estate Law Richard Jones – Litigation and Controversy/Tax; Tax Law Karen Kepler – Real Estate Law David Leahy – Mutual Funds Law David Mahaffey – Mutual Funds Law; Securities Regulation Lisa Mingolla – Trusts and Estates Louis Monti – Real Estate Law Cornelius Murray – Trusts and Estates David Nagle – Litigation and Controversy/Tax; Tax Law Nicholas O’Donnell – Commercial Litigation Ameek Ashok Ponda – Tax Law Domenick Pugliese – Mutual Funds Law Constantine Ralli – Trusts and Estates Gregory Sampson – Environmental Law; Real Estate Law; Land Use, Zoning Law Lewis Segall – Mergers and Acquisitions Law Amy Sheridan – Employee Benefits (ERISA) Law Laura Steinberg – Commercial Litigation Amy Zuccarello – Bankruptcy and Creditor Debtor Rights/Insolvency and Reorganization Law; Litigation/Bankruptcy The Sullivan attorneys listed as 2025 Ones to Watch®are: Steven Cunningham, Jr. – Trusts and Estates Caroline Kupiec – Tax Law Natalie Lederman – Corporate Law Michael Palmisciano – Intellectual Property Law Avinash Rao – Corporate Law Aaron Schleicher – Securities/Capital Markets Law Ashley Tan – Real Estate Law Ryan Tompkins – Tax Law, Trusts and Estates Shu Wei – Corporate Law About Sullivan Sullivan & Worcester (Sullivan) is a global, mid-sized law firm with lawyers in Boston, London, New York, Tel Aviv and Washington, D.C. Sullivan’s clients, including Fortune 500 companies, leading financial services firms and asset managers, boards of directors, real estate companies, and emerging businesses, rely on Sullivan’s ability to navigate complex legal and operational landscapes, the impeccable judgment of its lawyers, and its commitment to best‑in‑class client service.

Warren M. Heilbronner

Warren is a Partner in the Real Estate Department. Although his practice encompasses the entire range of commercial real estate law, he concentrates in the area of leasing.

44 Sullivan & Worcester Lawyers Named as “Best Lawyers” Award Recipients
Boston MA – Sullivan & Worcester today announced that 44 lawyers were recognized in the 2026 edition of Best Lawyers in America®. Three Sullivan partners also earned the 2026 “Lawyer of the Year” recognition from The Best Lawyers in America®. 39 of the firm’s lawyers in Boston, New York and Washington, D.C. were named as “Best Lawyers in America®,” and five Sullivan lawyers were recognized as “Ones to Watch” in the U.S. Lawyers of the Year David Nagle, managing partner of Sullivan, Amy Sheridan, and Lewis Segall were selected as "Lawyer of the Year" in Boston for Litigation and Controversy – Tax, Employee Benefits (ERISA) Law, and Mergers and Acquisitions Law, respectively. Only one lawyer is recognized as a "Lawyer of the Year" in each practice area and geographic location. These individuals are notable for receiving significantly higher ratings in Best Lawyers’ rigorous assessment process among the thousands of leading lawyers peer-reviewed in their markets. Best Lawyers in America® The firm’s 2026 Best Lawyers in Boston include Victor Baltera (Real Estate Law); Howard Berkenblit (Corporate Governance Law, Corporate Law); Harvey Bines (Corporate Compliance Law, Corporate Governance Law); Ashley Brooks (Real Estate Law); Joel Carpenter (Tax Law); Henry Comstock Jr. (Trusts and Estates); Christopher Curtis (Tax Law); Patrick Dinardo (Bankruptcy and Creditor Debtor Rights / Insolvency and Reorganization Law, Litigation – Bankruptcy); John Graham (Nonprofit / Charities Law, Tax Law); Ira Gross (Commercial Litigation); David Guadagnoli (Employee Benefits (ERISA) Law, Tax Law); Warren Heilbronner (Real Estate Law); Zachary Hyde (Patent Law); Richard Jones (Tax Law); Karen Kepler (Real Estate Law), Caroline Kupiec (Tax Law); Thomas Meyers (Patent Law); Lisa Mingolla (Trusts and Estates); Louis Monti (Real Estate Law); Cornelius Murray III (Trusts and Estates); David Nagle (Litigation and Controversy – Tax, Tax Law); Nicholas O'Donnell (Commercial Litigation); Ameek Ashok Ponda (Tax Law); Gregory Sampson (Environmental Law, Land Use and Zoning Law, Real Estate Law); Lewis Segall (Mergers and Acquisitions Law); Amy Sheridan (Employee Benefits (ERISA) Law); Laura Steinberg (Commercial Litigation); Sarah Wellings (Tax Law) and Amy Zuccarello (Bankruptcy and Creditor Debtor Rights / Insolvency and Reorganization Law, Litigation – Bankruptcy). Sullivan’s 2026 Best Lawyers in Washington, D.C. include John Chilton (Mutual Funds); Cameron Cosby (Tax); Nicole Crum (Mutual Funds); David Leahy (Mutual Funds); David Mahaffey (Mutual Funds & Securities Regulation); and Stephanie Monaco (Corporate, Mutual Funds, Private Funds / Hedge Funds, & Securities Regulation). The firm’s 2026 honorees in New York include Carole Bass (Trusts and Estates); J. Truman Bidwell, Jr. (Corporate); Domenick Pugliese (Mutual Funds); and Constantine Ralli (Trusts and Estates). Best Lawyers: Ones to Watch Awardees Best Lawyers awards this recognition to attorneys who are earlier in their careers for their outstanding professional excellence in private practice in the United States. Sullivan’s five lawyers earning this award include Alexander Gansebom (Corporate Governance and Compliance Law, Corporate Law, Health Care Law, Mergers and Acquisitions Law, Real Estate Law); Emily Goldschmidt (Corporate Law); Ryan Rosenblatt (Commercial Litigation); Ashley Tan (Real Estate Law); and Eric Victorson (Securities / Capital Markets Law). Best Lawyers Selection Methodology Recognition by Best Lawyers in America® is based on a peer review process designed to capture the consensus opinion of leading lawyers about the professional abilities of their colleagues within the same geographical and legal practice areas. About Sullivan Sullivan & Worcester (Sullivan) is a global, mid-sized law firm with lawyers in Boston, London, New York, Tel Aviv and Washington, D.C. Sullivan’s clients, including Fortune 500 companies, leading financial services firms and asset managers, boards of directors, real estate companies, and emerging businesses, rely on Sullivan’s ability to navigate complex legal and operational landscapes, the impeccable judgment of its lawyers, and its commitment to best‑in‑class client service.
33 Sullivan & Worcester Lawyers Recognized as Best Lawyers® Award Recipients
Boston, MA – Sullivan & Worcester announced today that 33 lawyers have been included in the 2025 edition of The Best Lawyers in America® and nine lawyers have been included in the 2025 edition of Best Lawyers: Ones to Watch®in America. Since it was first published in 1983, Best Lawyers has become universally regarded as the definitive guide to legal excellence. Best Lawyers has earned the respect of the profession, the media and the public as the most reliable, unbiased source of legal referrals. Its first international list was published in 2006 and since then has grown to provide lists in more than 75 countries. Lawyers on The Best Lawyers in America list are divided by geographic region and practice areas. They are reviewed by their peers based on professional expertise and undergo an authentication process to make sure they are in current practice and in good standing. Best Lawyers: Ones to Watch in America recognizes lawyers who are earlier in their careers for their outstanding professional excellence in private practice in the United States. The Sullivan attorneys listed as 2025 Best Lawyers in America®are: Victor Baltera – Real Estate Law Carole Bass – Trusts and Estates Howard Berkenblit – Corporate Governance Law; Corporate Law J. Truman Bidwell – Corporate Law Harvey Bines – Corporate Compliance Law; Corporate Governance Law; Corporate Law Ashley Brooks – Real Estate Law Joel Carpenter – Tax Law John Chilton – Mutual Funds Law Henry Comstock, Jr. – Trusts and Estates Nicole Crum – Mutual Funds Law Christopher Curtis – Tax Law Patrick Dinardo – Bankruptcy and Creditor Debtor Rights/Insolvency and Reorganization Law; Litigation/Bankruptcy John Graham – Non-Profit/Charities Law, Tax Law Ira Gross – Commercial Litigation David Guadagnoli – Employee Benefits (ERISA) Law; Tax Law Warren Heilbronner – Real Estate Law Richard Jones – Litigation and Controversy/Tax; Tax Law Karen Kepler – Real Estate Law David Leahy – Mutual Funds Law David Mahaffey – Mutual Funds Law; Securities Regulation Lisa Mingolla – Trusts and Estates Louis Monti – Real Estate Law Cornelius Murray – Trusts and Estates David Nagle – Litigation and Controversy/Tax; Tax Law Nicholas O’Donnell – Commercial Litigation Ameek Ashok Ponda – Tax Law Domenick Pugliese – Mutual Funds Law Constantine Ralli – Trusts and Estates Gregory Sampson – Environmental Law; Real Estate Law; Land Use, Zoning Law Lewis Segall – Mergers and Acquisitions Law Amy Sheridan – Employee Benefits (ERISA) Law Laura Steinberg – Commercial Litigation Amy Zuccarello – Bankruptcy and Creditor Debtor Rights/Insolvency and Reorganization Law; Litigation/Bankruptcy The Sullivan attorneys listed as 2025 Ones to Watch®are: Steven Cunningham, Jr. – Trusts and Estates Caroline Kupiec – Tax Law Natalie Lederman – Corporate Law Michael Palmisciano – Intellectual Property Law Avinash Rao – Corporate Law Aaron Schleicher – Securities/Capital Markets Law Ashley Tan – Real Estate Law Ryan Tompkins – Tax Law, Trusts and Estates Shu Wei – Corporate Law About Sullivan Sullivan & Worcester (Sullivan) is a global, mid-sized law firm with lawyers in Boston, London, New York, Tel Aviv and Washington, D.C. Sullivan’s clients, including Fortune 500 companies, leading financial services firms and asset managers, boards of directors, real estate companies, and emerging businesses, rely on Sullivan’s ability to navigate complex legal and operational landscapes, the impeccable judgment of its lawyers, and its commitment to best‑in‑class client service.