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Aaron M. May

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Aaron M. May is a founding partner of Halpern May Ybarra Gelberg LLP. Mr. May focuses his practice on complex commercial litigation, white collar criminal defense, and internal corporate investigations. He has tried numerous jury and bench trials, in federal and state courts. Mr. May has never lost a trial in which he was lead counsel.  The Daily Journal has named Mr. May one of the Top 100 Lawyers in California.

Mr. May was recently selected by the State Bar of California to conduct an independent investigation of the State Bar’s handling of disciplinary complaints against Tom Girardi and Mr. Girardi’s influence at the State Bar, which resulted in the publication of the “May Report.”  The State Bar explained that “Mr. May was chosen for his expertise, experience, and impeccable credentials.”

Previously, Mr. May was an Assistant United States Attorney in Los Angeles. In that capacity, he led some of the largest fraud investigations in the region and prosecuted individuals and corporations for sophisticated federal financial crimes, including health care fraud, false claims, securities violations, criminal trademark and counterfeiting, tax violations, money laundering, and loan fraud. At the U.S. Attorney’s Office, he held several leadership positions, including the office’s Securities Fraud Coordinator, Financial Institution Fraud Coordinator, and Procurement Fraud Coordinator. In these positions, he coordinated criminal prosecutions with the Securities and Exchange Commission, the Federal Bureau of Investigations, the Internal Revenue Service, the Defense Criminal Investigative Service, and other federal and state law enforcement agencies. Mr. May has also held Top Secret and SCI-level security clearances, which allowed him to work on matters pertaining to national security. This depth of experience on the prosecutorial side informs every aspect of his current defense work. 

Mr. May previously spent six years as a litigator at Munger, Tolles and Olson LLP. While there, he handled a wide array of complex civil litigation in disputes involving contract, trademark, tort, securities, malpractice and constitutional claims in state and federal courts across the country.

Mr. May began his legal career as a law clerk, first for the Honorable W. Matthew Byrne in the Central District of California and then for the Honorable Raymond Fisher in the Ninth Circuit Court of Appeals.

Mr. May received his J.D. from Stanford Law School, graduating second in his class and Order of the Coif. He completed his undergraduate studies at Brown University, where he received a B.A. in Public Policy and a B.S. in Environmental Science with honors and graduated magna cum laude

Mr. May is a Board Member and the Former President of the Housing Rights Center, the nation’s largest nonprofit, civil rights organization dedicated to promoting and securing fair housing.  He is also a Board Member of the Inner City Law Center, whose mission is to serve the poorest and most vulnerable residents of Los Angeles.  Mr. May is also a member of the Executive Committee of the Litigation Section of the Los Angeles County Bar Association, American Bar Association’s National Financial Institution Fraud sub-committee, and Federal Bar Association. 

He is admitted to practice law in California and before the United States District Courts for the Northern, Central, Eastern, and Southern Districts of California, the United States Courts of Appeals for the Fifth Circuit, Ninth Circuit and Federal Circuit and the United States Supreme Court. 


  • Stanford Law School, J.D. Order of the Coif, Stanford Law Review
  • Brown University, B.S. / B.A. Magna cum laude , Environmental Science and Public Policy

Representative Cases

In Private Practice:

  • Appointed by the State Bar of California to conduct an independent investigation into whether the State Bar's handling of past discipline complaints against Girardi was affected by Girardi’s connections to or influence at the State Bar
  • Successfully represented one of California’s largest companies in a multi-year criminal and civil DOJ investigation and in a qui tam action regarding allegations that the company was involved in a billion dollar fraud scheme. Even after the DOJ executed warrants at multiple locations, was able to convince the DOJ not to bring any criminal or civil charges against the client and to not join the qui tam, which was dismissed.
  • Won a $27 million jury verdict in federal court on behalf of firm’s client against medical device manufacturer NuVasive, Inc. and secured the dismissal of all of NuVasive’s claims
  • Represented the former CFO of one of the world’s leading financial institutions in connection with Department of Justice and SEC investigations. Successfully convinced the DOJ and SEC not to bring any charges against the client
  • Won motion to dismiss multi-million dollar securities fraud and other claims on behalf of founder of an entertainment company
  • Regularly conduct internal investigations for large, publicly traded corporations as well as private entities involving allegations of kickbacks, FCPA violations, health and safety issues, workplace harassment, and other matters.
  • Successfully defended multiple high profile professors and university administrator in connection with the DOJ’s China Initiative. Even after the DOJ executed search warrants at the professors’ home and laboratories, convinced the DOJ not to bring any criminal charges and to return all items seized.
  • Obtained the dismissal of homicide and insurance fraud charges against a physician accused of killing an infant by wrongfully prescribing unnecessary medications.
  • Won an $8.6 million arbitration award against Morgan Stanley for churning, unauthorized trading, and FINRA rule violations. The FINRA arbitration panel awarded $2.0 million in punitive damages and nearly $500,000 in attorneys’ fees and costs after finding that Morgan Stanley engaged in financial elder abuse
  • Obtained eight-figure settlement recovery for health care provider in connection with a breach of contract action
  • Won a motion to dismiss a multi-million False Claims Act case on behalf of an international energy company
  • Secured multi-million dollar recovery for the South Coast Air Quality Management District in its civil penalty action against the Southern California Gas Company for the Porter Ranch / Aliso Canyon Gas Leak
  • Convinced DOJ not to charge medical executive with any criminal offenses even after the government secretly recorded his conversations with others who were charged with crimes and client had confessed
  • Negotiated a multi-million dollar settlement recovery from a health care insurer for breach of contract
  • Obtained immunity from the Department of Justice for a client who was under investigation for Federal grant fraud
  • Obtained immunity from the Department of Justice for a media executive in a multi-million securities fraud investigation
  • Defeated multi-million federal lawsuit alleging that HYGM’s client, a $17 billion hedge fund, committed fraud in connection with restructuring of an employment services company
  • Convinced Department of Justice not to prosecute the president of a company for environmental and customs offenses where the company itself pled guilty to offenses
  • Obtained immunity from the U.S. Attorney’s Office for our client, an attorney who was under federal investigation for allegedly extorting intellectual property holders
  • Secured the dismissal of a federal lawsuit on behalf of HYGM’s clients, a hedge fund and its majority member, that alleged federal securities violations for insider trading and Section 16 violations
  • Represented a CEO before the SEC in a securities investigation, resulting in no charges being filed
  • Won anti-SLAPP motion on behalf of television production company and its CEO, resulting in dismissal of all claims
  • Obtained dismissal of trade-secret and breach of contract lawsuit on behalf of a high-level entertainment executive that was filed by the executive’s former employer after the executive moved to a competitor
  • Represented major movie studio in connection with a grand jury investigation
  • Successfully defended a director of a major financial services company in investigation brought by the Financial Industry Regulatory Authority (“FINRA”) alleging that director had disclosed material, non-public information and had falsified expense reports
  • Represented national law firm in multiple legal malpractice actions filed in state court and in arbitrations
  • Successfully sued Morgan Stanley on behalf of multiple clients for mishandling of clients’ brokerage accounts resulting in millions of dollars in damages
  • Provided securities advice regarding disclosures for one of California’s largest companies
  • Represent the Audit Committee of a financial institution as part of investigation into allegations of employee misconduct
  • Negotiated no jail plea agreement for star collegiate football player charged with multiple felony offenses
  • Secured the indefinite stay of a civil lawsuit alleging health care fraud on behalf of health care provider
  • Defended a national law firm against millions of dollars in malpractice claims in state and federal courts across the country
  • Represented two regional banks in separate matters that were victims of loan fraud schemes by working with federal law enforcement authorities and by helping the banks recover their losses through insurance coverage and other means
  • Defending multiple health care providers against lawsuits brought by large insurance companies alleging kickbacks, fraud and regulatory violations

As a Federal Prosecutor:

  • Led large team of federal and state investigators in billion-dollar healthcare and tax fraud investigation
  • Obtained across the board guilty verdicts against a former law firm partner for obstructing a Securities and Exchange Commission (“SEC”) investigation
  • Prosecuted professor at a large university for research fraud
  • In separate jury trials, convicted a doctor and another health care professional of health care fraud
  • Convicted, after a jury trial, a defense contractor for selling millions of dollars of counterfeit goods to the United States military
  • Participated in investigations resulting in over $100 million dollars in seized and forfeited assets


  • Hon. W. Matthew Byrne - U.S. District Court, Central District of California
  • Hon. Raymond Fisher - U.S. Court of Appeals, Ninth Circuit