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Est. 1987 — New York

Three decades of landmark victories. A relentless commitment to those we serve. Mercer & Black — where legal strategy meets unwavering advocacy.

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Recognized by
Justice is not a commodity. It is a calling we answer every single day.
— William Mercer, Founding Partner
Our Philosophy

A Firm Built on Principle, Forged in Courtrooms

Founded in 1987, Mercer & Black has grown from a two-attorney boutique into one of the nation's most respected litigation practices — without ever compromising the values that shaped us.

We take on the cases others consider too complex, too politically sensitive, or too consequential to risk. That is precisely why clients trust us with what matters most.

  • Ranked Tier 1 in 12 consecutive Legal 500 editions
  • $4.2 billion in total client recoveries
  • Attorneys admitted across 47 state bars
  • 8,000+ pro bono hours committed annually
What We Do

Practice Areas

Deep domain expertise backed by decades of precedent-setting litigation.

01

Corporate Law

Mergers, acquisitions, governance disputes, shareholder actions, and the full spectrum of corporate transactional work.

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02

Complex Litigation

High-stakes civil and commercial disputes, class actions, arbitration, and multijurisdictional litigation at every level.

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03

Mergers & Acquisitions

Strategic counsel through every phase — due diligence, negotiation, regulatory clearance, and post-merger integration disputes.

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04

Intellectual Property

Patent enforcement, trademark disputes, trade secret litigation, copyright, and IP portfolio strategy across all industries.

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05

Regulatory & Compliance

SEC investigations, antitrust matters, FCPA, healthcare regulation, environmental compliance, and government enforcement defense.

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06

International Arbitration

Cross-border commercial disputes, investment treaty arbitration, and enforcement of international awards in 60+ jurisdictions.

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Track Record

Landmark Recoveries

Representative outcomes. Past results do not guarantee future performance.

$210M
Corporate Fraud
$127M
Securities
$84M
Medical
$56M
Environmental
0Years of Practice
0Cases Resolved
0Client Recoveries
0Client Satisfaction
Our People

Meet the Team

Exceptional legal minds united by a shared commitment to client outcomes.

WM

William Mercer

Founding Partner

35 years at trial. Former SDNY prosecutor. Named to The American Lawyer's Hall of Fame.

DB

Diana Black

Senior Partner

International arbitration specialist. Fluent in 4 languages. Former ICC arbitrator with 80+ international awards.

JC

James Calloway

Partner, M&A

Led 200+ transactions exceeding $1B. Former Goldman Sachs GC. Harvard Law, magna cum laude.

SR

Sofia Reyes

Partner, IP & Tech

150+ patent trials. Named to Forbes Legal Power List three consecutive years.

Client Voice

What Clients Say

“

Mercer & Black recovered $127 million for our shareholders when every other firm said the case was unwinnable. Their command of securities law is simply unmatched.

Jonathan WhitmoreCEO, Whitmore Financial Group
WFG
since 2019
“

In 22 years of global business, I have never encountered attorneys of this caliber. They don't just understand law — they understand business at the highest level.

Amara Osei-BonsuChair, Meridian Capital Partners
MCP
since 2021
“

The IP team protected 14 years of our R&D investment. Sofia Reyes is simply the best patent litigator alive. Full stop.

Dr. Mei-Lin TsaoCTO, NovaBio Technologies
NBT
since 2022
Begin Your Case

Your matter deserves
relentless counsel.

Our attorneys are available for confidential consultations. The first conversation is complimentary.

Schedule a Consultation