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J. Gregory Deis

J. Gregory Deis

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Securities Investigations: Internal, Civil and Criminal

Securities Investigations: Internal, Civil and Criminal

Current Issues in Internal Corporate Investigations

Global Investigations Review 2018

Mayer Brown has been named to Global Investigations Review’s (GIR) list of the “world’s top 30 investigations practices” for the fourth consecutive year.

Greg Deis is a partner and Co-Chair of the Firm's White Collar Defense & Compliance practice. Greg has substantial expertise in conducting sensitive internal investigations and counseling clients on compliance programs, defending clients in criminal and regulatory proceedings, and serving as trial counsel in complex commercial litigation.

Greg has led domestic and cross-border internal investigations on behalf of a variety of clients across a wide range of industries. He regularly represents clients in investigations led by the Department of Justice, the Securities and Exchange Commission, state attorneys general, and other regulatory bodies. These matters have involved the FCPA, commercial bribery, the False Claims Act, competition laws, customs laws, US sanctions/OFAC, securities fraud, consumer fraud, tax, money laundering, and environmental offenses. Greg also routinely counsels clients on compliance programs and compliance audits/due diligence arising out of acquisitions and joint ventures.

Greg is a seasoned trial lawyer, having tried many criminal and civil cases in federal and state court and in arbitration, along with serving as lead counsel in numerous criminal and civil appeals. Greg's complex commercial litigation experience involves various areas of law, including RICO, federal and state securities law, Lanham Act claims, antitrust, tax controversy, environmental law, and shareholder derivative claims.

Prior to rejoining Mayer Brown, Greg served as an Assistant US Attorney in Chicago, assigned to the Public Corruption section. Greg prosecuted numerous public officials and law enforcement officers with fraud, bribery, extortion, and tax offenses, including the bribery prosecution of an Illinois state representative. His trial experience includes the month-long trial of William Cellini, a long-standing political insider in Illinois convicted of extorting campaign contributions for then Governor Rod Blagojevich. In addition to his corruption experience, Greg investigated and prosecuted a wide range of federal criminal cases involving complex financial fraud, money laundering, computer offenses and international drug trafficking, including the prosecution of members of the Los Zetas and Sinaloa cartels.

Greg maintains an active pro bono practice, including serving as a Panel Attorney for the Federal Defender Program in Chicago, representing indigent defendants in federal criminal proceedings.

Greg has been an adjunct professor of criminal procedure and trial advocacy at DePaul University College of Law and previously served on Law360's White Collar Editorial Advisory Board. Greg began his legal career as a law clerk for the Honorable Deanell Reece Tacha, Chief Judge of the US Court of Appeals for the Tenth Circuit.

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