Leron Thumim is a partner in the firm’s Litigation group. An experienced commercial litigator, his practice includes claims of breaches of contract and fiduciary duties, trademark disputes, and securities fraud litigation, as well as matters involving secured lien priority, real property, False Claims Act violations, legal and accounting malpractice, and employment-related claims, including allegations of sexual harassment, discrimination, and retaliation.

Leron represents clients at every stage of dispute resolution, including litigation in federal and state courts, as well as arbitrations, mediations, and internal investigations. He has particular depth in e-discovery and regularly advises clients in complex, document-intensive matters.

He works closely with clients to help them understand the legal and strategic dimensions of their disputes and to achieve favorable outcomes as efficiently as possible. Leron combines assertive advocacy with thoughtful, strategic decision-making, recognizing that effective representation often requires both strong litigation skills and a practical, non-confrontational approach when appropriate.

Leron is regarded for his clear and persuasive written and oral advocacy, strong negotiation skills, and ability to develop creative, results-oriented strategies. His approach to disputes includes reassessing litigation tactics to ensure the most effective and efficient path forward.

Prior to joining A.Y. Strauss, Leron previously worked at several highly regarded firms including Quinn Emanuel Urquhart & Sullivan LLP, McDermott Will & Emery LLP and Brown Rudnick LLP. Earlier in his career, he held a clerkship under the Honorable Shira A. Scheindlin in the Southern District of New York.

He has been recognized by Super Lawyers (New York Metro) for his work in Business Litigation (2024 – 2026), as well as Super Lawyers Rising Stars (New York Metro) for Business Litigation (2018 – 2023). He was also named to Best Lawyers “Ones to Watch” list in 2023 and 2024.

Representative Matters

• Won a post-asset acquisition working capital “true-up” arbitration on behalf of a large multinational company, obtaining an eight-figure arbitration award plus fees.
• Represented majority owner of a business in an action by the minority owners; won dismissal claims, then conceived of and negotiated a complicated buyout that spared all parties years of expensive and protracted litigation.
• Acted as lead counsel representing a multinational FinTech company in a trademark dispute against a national bank through depositions, expert discovery, and mediation.
• Represented an investor alleging securities fraud and market manipulation in claims against national banks, prevailing on multiple motions to dismiss.
• Won an arbitration on behalf of former employees who had not been paid contractually-mandated success fees, obtaining an award that included attorneys’ fees and interest.
• Represented family owners of a high-end apartment building in a dispute against a contractor who was alleged to have engaged in self-dealing, breaches of contract, waste, and more.
• Represented several hedge funds in disputes against former asset managers and employees who breached their applicable agreements.
• Won release of a levy on investment property by a judgment creditor, on behalf of a first-secured creditor (Maryland Federal Court).
• Represented the former chairman of a for-profit private college in claims brought by a labor union to enforce an arbitration award against now bankrupt college; obtained dismissal on motion to dismiss of all but one claim. Represented the same client and a for-profit private college against claims brought by various merchant lenders seeking to collect on loans; obtained dismissal of claims on motion.
• Accepted a district court’s request to represent an inmate (pro bono) at Sing Sing Correctional Facility in a § 1983 prisoner civil rights case that alleged violations of the inmate’s Sixth Amendment right to be free from cruel and unusual punishment. Ultimately secured necessary medical treatment for the inmate, along with a favorable, five-figure settlement.
• Successfully represented a parolee (pro bono) in a parole revocation hearing, securing treatment for the parolee in lieu of years of reincarceration.

Publications/Presentations

• New York State Bar Association – “Litigation Issues in Contract Drafting”
• Co-Taught a CLE course on “No Oral Modification” Clauses – Enforcement and Exceptions.”
• New York State Bar Association – “Ethics and E-Discovery: Dos, Don’ts, and Really Don’ts”

Honors, Awards & Recognitions

• Super Lawyers New York Metro, Business Litigation (2024 – 2026)
• Super Lawyers New York Metro Rising Stars, Business Litigation (2018 – 2023)
• Best Lawyers Ones to Watch (2023 – 2024)