Michael B. de Leeuw

Vice Chair, Business Litigation

New York

(212) 908-1331

(212) 509-9492

Michael will be speaking at an upcoming event:

Securities Litigation, Arbitration, and Regulatory Investigations in the COVID-19 (and hopefully Post-COVID-19) World

Webinar 06/04/2020

Webinar - June 4, 2020

Event Details 

Michael is a skilled litigator whose experience includes a variety of high-profile matters spanning many areas of law in federal and state courts throughout the country. He has extensive experience in securities litigation, antitrust litigation, First Amendment and defamation matters, and disputes arising out of mergers and acquisitions, both at the trial and appellate levels. Michael is a member in Cozen O’Connor’s Commercial Litigation Department and vice chair of the firm’s Business Litigation Group.

In 2019, Michael briefed, argued, and won a major First Amendment case at the United States Supreme Court:  In Manhattan Community Access Center v. Halleck, the Supreme Court reversed the Second Circuit Court of Appeals and clarified the critical constitutional question of when private parties can be deemed “state actors” and thus potentially liable for constitutional violations.

Michael is active in bar and civic organizations. He is on the board of the Lawyers' Committee for Civil Rights Under Law; served as co-chair of the Antitrust Litigation Committee in the Litigation Section of the ABA; and is also an elected member and vice president of the Board of Education in Glen Ridge, N.J.

Michael earned his law degree from Rutgers University School of Law, graduating with honors and as a member of the order of the coif. He was editor-in-chief of the Rutgers Computer & Technology Law Journal. He received his bachelor's degree from Montclair State University, majoring in philosophy and then continued his study of philosophy in graduate school at Rutgers University.



17 Cozen O’Connor Attorneys Recognized as New York Super Lawyers and Rising Stars

September 27, 2019

Super Lawyers has named 17 Cozen O'Connor attorneys to its 2019 New York Super Lawyers and Rising Stars list.

Cozen O’Connor Team Wins Landmark First Amendment Ruling

June 21, 2019

The team includes Michael de Leeuw, Stuart Shorenstein, Tamar Wise, Stephen Miller, Jesse Loffler, William Lesser, and Anna Hanke.

18 Cozen O'Connor Attorneys Named New York Metro Super Lawyers and Rising Stars

September 21, 2018

Super Lawyers has named 17 Cozen O'Connor attorneys to its 2018 New York Super Lawyers and Rising Stars list. Twelve were recognized as Super Lawyers and five were named "Rising Stars."

12 Cozen O’Connor Attorneys Named 2017 New York Metro Super Lawyers and Rising Stars

October 19, 2017

Super Lawyers has named 12 attorneys at Cozen O’Connor to its 2017 lists of top practitioners in the New York metro area. Six were recognized as Super Lawyers and six were named “Rising Stars,” a list that recognizes attorneys under the age of 40.

Cozen O’Connor Names Six New Shareholders

September 07, 2017

Cozen O’Connor is proud to announce the promotion of six members to shareholders of the firm: David Brisco (San Diego), Michael de Leeuw (New York), John Dickenson (West Palm Beach), Jonathan Lichtenstein (Philadelphia), William Walsh (Seattle), and Ingrid Welch (Philadelphia).

Cozen O’Connor Team Partners with NAACP to Win Historic Voting Rights Victory

August 30, 2017

Cozen O’Connor, alongside co-counsel NAACP Legal Defense and Educational Fund (LDF) and New Orleans-based civil rights lawyer Ron Wilson, obtained an important trial victory for our clients—the Terrebonne Parish NAACP and four individual Black voters—in a voting rights case in the United States District Court for the Middle District of Louisiana.

19 Cozen O'Connor Attorneys Recognized as New York Super Lawyers and Rising Stars

October 05, 2016

The 2016 New York Metro edition of Super Lawyers Magazine, published by Thomson Reuters, has named 21 Cozen O’Connor attorneys to its list of Super Lawyers and Rising Stars.

21 Cozen O'Connor Attorneys Recognized as New York Super Lawyers and Rising Stars

October 05, 2015

The 2015 New York Metro edition of Super Lawyers Magazine, published by Thomson Reuters, has named 21 Cozen O’Connor attorneys to its list of Super Lawyers and Rising Stars.

Michael de Leeuw Discusses 2015's Securities Cases to Watch in Law360

January 02, 2015

In an article titled ''Securities Cases To Watch In 2015,'' Michael de Leeuw, a member of Cozen O’Connor’s Commercial Litigation Department, comments on the closely watched Supreme Court case Omnicare Inc. et al. v. Laborers District Council Construction Industry Pension Fund et al. and the Second Circuit’s recent decision in US v. Newman et al.

16 Cozen O’Connor Attorneys Recognized as New York Super Lawyers and Rising Stars

September 23, 2014

The 2014 New York Metro edition of Super Lawyers Magazine, published by Thomson Reuters, has named 16 Cozen O’Connor attorneys to its list of Super Lawyers and Rising Stars.

Cozen O'Connor Grows Litigation Team in New York with Five New Partners

October 15, 2013

Cozen O’Connor continues to increase the depth of the firm’s litigation capabilities in New York with the recent hiring of five new partners. Partners residing in the firm's New York office who have joined in recent months include John J. Sullivan, Michael B. de Leeuw, Patrick B. Sardino, William K. Kirrane and Adam I. Stein.


COVID-Driven Commercial Litigation – What Businesses Can Expect

May 08, 2020

Adam Schlatner and Michael de Leeuw discuss potential COVID-19 related litigation, based on what is already happening and the legacy of other downturns.

Litigation During the Pandemic: Remote Depositions [Alert]

April 23, 2020

Michael de Leeuw, Adam Schlatner, and Amy Alderfer discuss things to consider before taking your first remote deposition.

Supreme Court Limits First Amendment Exposure of Social Media Giants [Silicon Valley Business Journal]

July 11, 2019

Michael B. de Leeuw and Tamar Wise contributed an article to Silicon Valley Business Journal discussing the Manhattan Community Access Center v. Halleck (MCAC) case.

‘Possession, Custody or Control’—Got It?

April 11, 2018

Michael de Leeuw, a member in the firm's Commercial Litigation Department, authored, " ‘Possession, Custody or Control’—Got It?" for the New York Law Journal.

A Series of Very Unfortunate Events [New York Law Journal]

October 31, 2016

Jonathan Grossman, Thomas Ingalls and Michael de Leeuw, members of Cozen O'Connor's Commercial Litigation department discuss the recent Caledonia matter in the New York Law Journal.

The Business Side of Justice Scalia [Corporate Counsel]

May 13, 2016

Michael de Leeuw and Matthew Elkin, both of Cozen O'Connor's Commercial Litigation department, discuss the business side of Justice Scalia in Corporate Counsel.

‘Irreparable Harm’ Is a Tough Hurdle to Clear [New York Law Journal]

February 23, 2015

In an article titled '''Irreparable Harm' Is a Tough Hurdle to Clear,'' Michael de Leeuw and John Sullivan, members of Cozen O'Connor's Commercial Litigation Department, examine the current state of preliminary injunction jurisprudence in New York courts (with liberal reference to their federal counterparts), in particular the treatment of the “irreparable harm” branch of the test, and explore whether there are any better guiding standards that might make preliminary injunction practice more predictable.

ESOPs’ Fables: On Winning Wars but Losing Battles [Class Action Defense Review Blog]

July 03, 2014

As the end of the Supreme Court term approached, decisions came down fast and furious. Last week’s big decisions, at least around our nerdish water cooler, were Halliburton and Fifth Third Bancorp v. Dudenhoeffer. (Yes, we know that there were major rulings on Obamacare, public unions, buffer zones,...

Halliburton Decided! World Does Not End [Class Action Defense Review Blog]

June 23, 2014

This morning the Supreme Court released its highly-anticipated decision in Hallburton Co. v. Erica P. John Fund, Inc.  As we (and, to be fair, others) predicted after the oral argument, the Court did not have the appetite to overturn Basic Inc. v. Levinson (though Justices Thomas, Scalia and Alito...

Tech Titans Settle Wage Antitrust Case [Class Action Defense Review Blog]

May 01, 2014

As often happens in the vicinity of courthouse steps, the high-profile Silicon Valley hiring antitrust class-action lawsuit has settled, pending court approval. In re: High-Tech Employee Antitrust Litigation originally pitted five software engineers as representatives of a broad putative class of...

Fear and Trebling: E-Book Class Action Takes a(nother) Bite out of Apple [Class Action Defense Review Blog]

April 17, 2014

The legal drama continues for Apple, Inc., as the tech giant recently suffered another in a string of significant legal setbacks in the e-book antitrust saga in the Southern District of New York.  Last month, Judge Denise Cote granted the plaintiffs’ motion for class certification, allowing e-book...

No Silver Lining for Plaintiffs as J.P. Morgan Defeats Silver Market Manipulation Suit [Class Action Defense Review Blog]

April 07, 2014

History has shown that large class action cases often follow government investigations the way that the lamb followed Mary to school that day.  Sometimes, however, those investigations die and Mary gets lost and brings her little lamb to the slaughterhouse.  The Second Circuit recently affirmed...

Back to Basic? Big Changes Could Be Coming to a Securities Class Action Near You [Class Action Defense Review Blog]

March 26, 2014

Earlier this month, the Supreme Court heard the highly-anticipated oral argument in Hallburton Co. v. Erica P. John Fund, Inc.  Prior to the argument, there was a growing consensus that the Court was likely going to overturn Basic Inc. v. Levinson (1988), the groundbreaking case that adopted the...

E-Discovery: Amendments Propose Extending 'Meet and Confer' Requirement [New York Law Journal]

March 18, 2013

The era when a lawyer can competently practice without understanding a client's electronic data is rapidly drawing to a close. New York's Office of Court Administration has recommended amendments to the rules governing preliminary conferences in non-Commercial Division cases that should radically reduce the number of cases where one can stand in front of a judge like Saturday Night Live's fabled unfrozen caveman lawyer, proudly ignorant of electronic discovery issues.

Time to Revisit The Ethics of Metadata [New York Law Journal]

March 19, 2012

More than 10 years ago, at a time when much uncertainty surrounded issues related to electronic documents, the New York State Bar Association Committee on Professional Ethics issued one of the first opinions addressing a lawyer’s ethical obligations concerning metadata.

Litigation: Use the Preliminary Conference to Save E-Discovery Costs [New York Law Journal]

April 18, 2011

All too often in today’s litigation environment, electronic discovery issues turn into expensive deathtraps that threaten to overwhelm the merits of the actual dispute between the parties. But prepared litigants can and should take measures to avoid the “gotcha” pitfalls attendant to e-discovery long before the terabytes have been put through the thresher.

Litigation: E-Discovery Oft-Overlooked Price Driver [New York Law Journal]

November 15, 2010

The costs associated with the discovery of electronically stored information (ESI) continue to increase at rates unknown outside of the healthcare industry. While much of the discussion regarding costs centers on those associated with accessing, reviewing and producing ESI, an oft-overlooked but (in many cases) significant driver of the high price of discovery are the costs associated with preserving ESI.

The Phantom Menace [New York Law Journal]

March 22, 2010

At this point in the discovery revolution, there is no question that savvy litigants have become sensitive to the need to preserve documents and, particularly, electronically stored information (ESI). While the cost of even marginal preservation steps can be quite high, the failure to act promptly can lead to the unintentional loss of documents (through the recycling of disaster recovery backups or the operation of automatic deletion routines in e-mail mailboxes) and unpleasant litigation consequences.

En Banc Review in the Second Circuit [New York Law Journal]

December 18, 2009

Much has been written about the Second Circuit’s decision (by a panel that included now-Associate Justice Sonia Sotomayor) to affirm the district court’s grant of summary judgment to the City of New Haven in Ricci v. DeStefano. Ricci was subsequently reversed by the U.S. Supreme Court and became a major topic of discussion during Justice Sotomayor’s confirmation hearing. Commentators and senators cited Judge Jose Cabranes’ forceful dissent from the Second Circuit’s decision not to grant a rehearing en banc, particularly his comment that the case raised “novel questions of constitutional and statutory law” that the Second Circuit’s decision had “failed to grapple with.”

Ready, Aim, Fire? District of Columbia v. Heller and Communities of Color [Harvard Black Letter Law Journal]

July 07, 2009

The Supreme Court’s recent decision in District of Columbia v. Heller held that a municipal ban on handguns is unconstitutional under the Second Amendment, but left open the possibility of reasonable regulations on firearms. Given the outrageous levels of firearms-related violence in many urban areas—violence that disproportionately affects communities of color—the question of what constitutes a reasonable regulation should be an issue of major concern to civil rights activists and lawyers. This article evaluates Heller in light of these issues, and argues in favor of a general presumption that local legislatures are best situated to balance the costs and benefits of firearms regulations. Moving forward, municipalities should be afforded broad discretion in enacting such regulations, consistent with the Court’s decision in Heller.

Ignore Climate Change at Your Peril [Law360]

March 24, 2009

The topic of climate change has become a significant public policy issue that has generated substantial discussion, controversy and debate. Recently, Steven Napolitano and Lincoln Wilson published an arresting article in Environmental Law 360 called “Why Climate Suits May not be ‘Next Big Thing.’”

A Cavalier Attitude [The National Law Journal]

August 06, 2008

While much commentary has been devoted to the groundbreaking holding of D.C. v. Heller — that the Second Amendment confers an individual right to "keep and bear Arms" for purely private purposes — too little attention has been paid to what the court did not decide and the significant uncertainties that remain in Second Amendment jurisprudence.

Beware the Digital Minefield [New York Law Journal]

May 19, 2008

While the collection, review and production of e-mails and other electronic documents have become routine for U.S. companies involved in civil litigation, internal investigations, and various other legal matters, there is an increasing number of cases that involve foreign or multinational clients, and the collection and production of electronic documents from these clients can be anything but routine.

Pennsylvania Ave.: A Key Decision for Joint Bidding [Law360]

March 19, 2008

A federal district court judge in the Western District of Washington recently dismissed an antitrust class action suit alleging that two private equity funds had unlawfully conspired in their bid to acquire WatchGuard Technologies (“WatchGuard”), a publicly traded company. Pennsylvania Avenue Funds v. Borey, Number C06-1737RAJ (W.D. Wash. Feb. 21, 2008).

E-Discovery: OMG! We Forgot to Produce IMs [New York Law Journal]

November 05, 2007

By now, most litigators have come to grips with e-mail and its many problems. We know that the ubiquity and shear volume of e-mail have changed civil discovery forever. We have all become familiar with our clients’ e-mail systems and their policies and procedures for the use and maintenance of e-mail. At the outset of a case we seemingly now spend more time with IT professionals than with in-house counsel, and we all know that it is important how often and when email servers are backed up and where files are stored. What many of us and our clients do not know (or are only learning now) is that millions of employees have been sending millions of messages to each other and to third parties each day—messages that completely circumvent all of the policies, processes and procedures that have diligently been put in place to control the e-mail monster.

New Partners: Crossing Over: How to keep your friends at the firm as friends, after the transition [New York Law Journal]

February 05, 2007

A friend who recently made partner at a large New York firm described the experience perfectly: After nine years of hard work and after an almost unbearable year and a half of backdoor politics, rumors, innuendo and insomnia, he received the long-awaited news that he had made the grade.

Litigation: Oh, What Litigators Dare Do [New York Law Journal]

December 04, 2006

There are few things more vexing to litigators than adverse parties who—despite the issuance of a court order—simply refuse to comply with their obligations under the law. Whether it is a discovery order mandating disclosure of certain documents or an injunction prohibiting the adverse party from engaging in specified conduct, we have all experienced the frustration of attempting to enforce court orders against recalcitrant or obstreperous adverse parties who flout such orders even under the threat of a possible contempt motion.

Litigation: What Is a Willful Breach of Contract? [New York Law Journal]

April 03, 2006

Michael B. de Leeuw co-authored this article for the New York Law Journal on why it is necessary to clarify ambiguous terms in commercial agreements.

Opening up the CAN-SPAM Act [Computers & Law]

February 29, 2004

The first United States federal law placing restrictions on the use of unsolicited commercial e-mail (UCE), or 'spam', went into effect on 1 January 2004. While it is early days yet, the reactions of both anti-spam activists, and of spammers, to the new provision, known as the Controlling the Assault of Non-Solicited Pornography And Marketing Act of 2003 ('CAN-SPAM' or the 'Act'), suggests that the Act is unlikely to have much effect in stemming the rising tide of spam messages (many originating from US spam gangs) that is clogging mailboxes the world over. Some of the apparent weaknesses of CAN-SPAM as an effective tool to thwart spam may arise from dubious drafting decisions, and some may be reflective of endemic shortcoming of any attempts to control spam by national legislation, given the inherent fluidity and anonymity of e-mail distribution through the Internet.

Spam After Can-Spam: How Inconsistent Thinking Has Made a Hash out of Unsolicited Commercial E-Mail Policy [Santa Clara Computer & High Technology Law Journal]

January 01, 2004

The authors of the Controlling the Assault of Non-Solicited Pornography And Marketing Act of 2003 (hereinafter, "CAN-SPAM" or the "Act"),' the first United States federal law placing restrictions on the use of unsolicited commercial e-mail ("UCE"), or "spam," were asking for trouble. First, the title of the Act rings of Orwellian doublespeak. Second, its content has drawn ire from all sides except, for the most part, the direct marketers who are the ones being regulated - and that is not a good sign.

Events & Seminars

Upcoming Events

Past Events

Litigating through the Coronavirus

April 17, 2020 - Webinar


  • Rutgers University School of Law—Newark, J.D., cum laude, 1996
  • Montclair State University, B.A., 1989

Awards & Honors

New York Super Lawyer 2014-2019

Burton Award for Excellence in Legal Writing

Legal 500


  • New Jersey
  • New York
  • U.S. Supreme Court
  • U.S. Court of Appeals for the Second Circuit
  • U.S. Court of Appeals for the Fifth Circuit
  • U.S. Court of Appeals for the Eleventh Circuit
  • U.S. District Court -- Southern District of New York
  • U.S. District Court -- Northern District of New York
  • U.S. District Court -- New Jersey
  • U.S. District Court -- Eastern District of Michigan
  • U.S. District Court -- Southern District of Mississippi