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Marc A. Wallenstein

Marc Wallenstein
312 641 9750
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800 678 9529
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Marc A. Wallenstein is a partner at the firm.  Marc is an experienced trial and appellate advocate who has spent his career holding wrongdoers accountable. Marc is a former federal prosecutor and has tried numerous cases to verdict.  Marc is undefeated before the United States Court of Appeals for the Ninth Circuit, having won all ten of the appeals in which he served as lead counsel.


Marc currently leads two parallel class action lawsuits against Google on behalf of users of Android mobile phones in California and nationwide. Marc recently won class certification on behalf of approximately 13 million California Android users, and won an appeal before the Ninth Circuit on behalf of Android users nationwide, reversing the district court’s dismissal of the complaint. Marc’s advocacy resulted in a unanimous decision issued just two weeks after oral argument.


Marc served as trial counsel for thousands of minor league baseball players who won the right to be paid minimum wage by Major League Baseball. The lawsuit reached a landmark $185 million settlement on the eve of trial, which represented 137% of the unpaid wages owed to class members—far in excess of a typical class action settlement. The resolution includes significant injunctive relief that will vindicate the rights of current and future minor league players for years to come.  In approving the settlement, the trial court wrote that counsel “has handled this case skillfully and with professionalism, diligently pursuing the interests of the players.  The significant relief they have obtained under the Settlement Agreement is, in no small part, due to their expertise and dedication.”


Marc serves as part of the lead or co-lead counsel teams in two additional cases against Google.  Marc took numerous depositions leading up to a proposed $700 million settlement-in-principal, in a lawsuit challenging Google’s anticompetitive practices regarding the fees it charges to developers of apps distributed through the Google Play Store.  And Marc is pursuing antitrust claims against Google arising out of its monopolization of the online advertising market, in which Google acts as the buyer’s agent, the seller’s agent, and the marketplace, all at the same time.

Before joining Korein Tillery, Marc served for six years as an Assistant U.S. Attorney in the District of Hawaii, where he gained expertise in national security matters, financial crime, procurement fraud, health care fraud, real estate fraudpublic corruption, cyber crime, environmental crime, and crimes against children.  Marc served as Computer Hacking and Intellectual Property (CHIP) Coordinator, responsible for complex issues related to computer crime and electronically stored information; as an Anti-Terrorism Advisory Coordinator (ATAC), responsible for national security investigations and prosecutions; as the National Parks coordinator; and as a member of the Department of Justice’s Cryptocurrency Working Group.  Marc successfully prosecuted the first terrorism case ever brought against an active duty member of the U.S. military. Marc obtained record fines in numerous environmental cases, including the largest marine pollution fine in District history, and the largest criminal penalty ever imposed in a shark fin trafficking case in the United States.  Marc has received several awards from the Department of Justice and the Federal Bureau of Investigation for his work and has taught national security investigations and prosecutions to fellow prosecutors and agents at the Department of Justice's National Advocacy Center.


At his final court appearance as an Assistant United States Attorney, the presiding district judge remarked:

And I’d like to take this opportunity to thank Mr. Wallenstein for his service to this Court and to the District of Hawaii. We will miss you, and your representation has always vigorous and very fair with an eye to justice, which I'd like to say is typical of all U.S. Attorneys, but is not, and so I mostly appreciate your personal talents but also your consistent value of ensuring a just outcome. We will particularly miss your baritone voice. But I’m sure that you’ll go on to great success in private practice, and I hope that you’ll return often to visit or perhaps appear in the District of Hawaii. But thank you very much for your service.

Prior to his time at the Department of Justice, Marc served for three years as a Prosecutor at the Office of the Chief Prosecutor of Military Commissions, U.S. Department of Defense.  In that capacity, Marc prosecuted violations of the law of war committed by enemy alien belligerents before a military commission in Guantanamo Bay, Cuba.  Among other responsibilities, Marc served as a litigation team chief, managing attorneys, paralegals, FBI agents, analysts, and staff.  Marc also served as an appellate and pretrial motions attorney on a range of cases, including the prosecution of Khalid Shaikh Mohammed and four others accused of perpetrating the attacks of September 11, 2001.

Marc successfully maintained an active Top Secret/SCI security clearance for a decade throughout his federal employment.

Marc previously conducted complex civil litigation in Washington DC at Kellogg Hansen PLLC.  Among other matters, he represented the National Credit Union Administration—an independent federal government agency—against Wall Street banks for failed investments in residential mortgage-backed securities, with co-counsel from Korein Tillery. The two firms ultimately recovered $5.1 billion—among the largest non-class recoveries in any type of litigation, ever. He also conducted a confidential internal investigation of a multination oil company, and managed all stages of a non-intervened qui tam lawsuit against the world's largest biotechnology company, which resulted in a $762 million global settlement on the eve of the trial. 

Marc is a graduate of Harvard College and Yale Law School. After law school, he served as a law clerk in the Southern District of New York and on the United States Court of Appeals for the Ninth Circuit.

Marc is admitted to practice law in New York, Washington DC, Texas, Hawaii, Connecticut, and numerous federal district and circuit courts around the country.

Before he became an attorney, Marc worked as a travel writer in Italy, Australia, and Hawaii. 


In his spare time, Marc teaches a semester-long course in Trial Practice at Yale Law School.  Marc previously taught legal research and writing at the University of Hawaii Richardson School of Law.

Marc lives in New Haven, Connecticut, with his wife Michelle and their rescue mutt Ben. 

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