Former Assistant U.S. Attorney Marc Wallenstein Joins Korein Tillery

Distinguished former federal prosecutor Marc Wallenstein has joined plaintiffs’ complex-litigation firm Korein Tillery as a partner. With a strong early-career background in private practice, representing consumers and institutional clients in class and private actions, he brings more than a decade of experience prosecuting an array of high-stakes matters on behalf of the United States government.


Based in Honolulu, Marc most recently served for six years as an Assistant U.S. Attorney in the District of Hawaii, focusing on national security matters, financial crime, procurement fraud, health care fraud, public corruption, cyber crime, environmental crime and crimes against children. In this role he served as Computer Hacking and Intellectual Property (“CHIP”) Coordinator, Anti-Terrorism Advisory Coordinator (“ATAC”) and a member of the Department of Justice’s Cryptocurrency Working Group. Marc prosecuted the first terrorism case against an active duty member of the U.S. military, and obtained record fines in numerous environmental cases, including the largest marine pollution fine in District of Hawaii history.


Prior to his DOJ service, Marc served for three years as a prosecutor at the Office of the Chief Prosecutor of Military Commissions, U.S. Department of Defense. Among other responsibilities, he was 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 first collaborated with Korein Tillery as an associate at Kellogg, Hansen, Todd, Figel, and Fredrick PLLC when the firms served as co-counsel representing the National Credit Union Administration (“NCUA”) against Wall Street banks for failed investments in residential mortgage-backed securities. The firms’ efforts have led to recoveries of $5.2 billion to date.


“We know from our previous work with Marc that he will embody Korein Tillery’s aggressive advocacy from concept to verdict,” said Korein Tillery founder and senior member Stephen Tillery. “His complex litigation prowess in both the public and private sector will be a tremendous benefit to our clients.”


At Korein Tillery, Marc will handle a broad range of complex litigation including, most immediately, working on the firm’s ongoing cases in California state and federal courts against large tech companies for antitrust violations in the online advertising auction market, anticompetitive app store activities, conversion of user data and unlawful treatment of copyright holders.


“I knew I wanted to continue holding wrongdoers accountable and serving the public interest when moving back to civil litigation,” said Marc. “Korein Tillery’s immense success on behalf of both consumers and commercial clients—which I’ve witnessed firsthand—made it the obvious choice.”


Marc graduated cum laude from Harvard College and earned his J.D. from Yale Law School. He then served as a law clerk in the Southern District of New York and the United States Court of Appeals for the Ninth Circuit. He is admitted to practice law in New York, Washington, D.C., Texas, Hawaii and numerous federal district and circuit courts nationwide.


About Korein Tillery


Korein Tillery—based in St. Louis and Chicago—is one of the country’s leading plaintiffs’ complex-litigation firms, representing a broad array of clients in high-stakes lawsuits. The firm bridges the historical divide between the resources, quality-of-representation, and national coverage offered by large, full-service law firms and the creativity, agility, and financial flexibility offered by boutique litigation practices.