“He is experienced in representing early adopters and innovators in the FinTech sector and is ‘known as the guy you contact when you get in trouble’.”

Chambers & Partners, 2020 Fintech Guide

“Brian Klein has been named one of the top 4 financial technology attorneys in the U.S. ”


“Partner Brian Klein’s extensive experience with cutting-edge technology cases has earned him a coveted spot on National Law Journal’s Trailblazers in Technology Law list.”

“One of the Top 100 Attorneys in California”

Daily Journal 2022

“Brian Klein is who you call if you’re facing cybercrimes charges. He knows the tech and no one will fight harder for you.”

Marcus Hutchins, Malware Researcher who stopped the WannaCry ransomware attack

Brian Klein

An accomplished and renowned trial attorney, Brian Klein is known for fierce and successful advocacy for his clients in a wide variety of federal and state forums across the country. He is a former federal prosecutor who handles high-stakes civil litigation and criminal and regulatory defense matters, including those involving the DOJ, SEC, CFTC, FTC, CFPB, and state authorities.

Brian’s clients are successful entrepreneurs and professionals, fast growing and innovative companies, as well as larger companies facing existential legal threats, often with a focus on the technology and finance industries. Based on his accomplishments, Brian has been recognized as one of the nation’s top five financial technology attorneys, one of the top 100 attorneys in California, and Chambers has noted that he is “known as the guy you call when you get in trouble.

”A leading legal player in the technology and finance industries, Brian chairs the annual American Bar Association’s blockchain and digital currency national institute. He also speaks internationally about cutting-edge litigation issues involving NFTs, data privacy, cyber security, and financial technology, and for years has taught a federal criminal practice seminar at the USC Gould School of Law.

Brian is admitted to practice in the states of California, Washington, and New York and before numerous federal courts around the country, including the Central and Northern Districts of California and the Southern and Eastern Districts of New York, as well as the U.S. Supreme Court.

He graduated from New York University School of Law and received his undergraduate degree from the University of Washington.

Representative Matters

  • Representing Frances Haugen, the “Facebook Whistleblower,” including appearing with her when she testified before the U.S. Senate.
  • Defended Arthur and Kathleen Breitman, as well as their company, in connection with securities class action lawsuits in San Francisco involving the Tezos crowdfunding, which raised over $230 million.
  • Represented in connection with its settlement with the SEC in which it paid a $24 million penalty in connection with its $4 billion token sale.
  • Defended Marcus Hutchins, who is known worldwide for stopping the “WannaCry” ransomware attack in May 2017, in a federal prosecution out of Milwaukee for cybercrimes from his youth. Marcus pleaded guilty, was sentenced to no prison time, and without precedent, the district court encouraged him to seek a pardon.
  • Successfully defended a digital currency trader in federal court in Colorado against an unlicensed money transmitter criminal charge, securing dismissal of the case before trial.
  • Obtained a complete acquittal at a jury trial in New York City for a boxer charged with assault with a deadly weapon in state court.
  • Secured a no action letter from the SEC in connection with a years long investigation of a major digital token offering.
  • Successfully handled the defense of Cesar Millan (the “Dog Whisperer”) when the Los Angeles County Department of Animal Control and District Attorney’s Office investigated allegations of animal abuse tied to one of Mr. Millan’s television shows. The authorities ultimately concluded Mr. Millan did nothing wrong and did not bring any charges.
  • Obtained a declination to bring charges for a client from federal prosecutors in San Diego in a money laundering-related case.
  • Represented Erik Voorhees, a prominent early Bitcoin adopter, in his settlement with the SEC in an investigation.
  • Secured from the Los Angeles County District Attorney’s Office a declination to charge a high-profile client accused of sexual assault by someone the client met on a dating app.
  • Represented a film production company in a Los Angeles-based federal action to enforce trademark rights that resulted in a settlement favorable to the client.
  • Successfully defended a digital currency company in a state securities division investigation based out of the Midwest (no enforcement action was brought).
  • Represented a U.S.-based technology company in a contract dispute with an Australian entertainment company that resulted in a settlement favorable to the client.
  • Successfully defended a hazardous waste cleanup company facing multiple California state criminal charges, securing dismissal of all charges before trial.

Professional Associations and Memberships

  • American Bar Association
  • National Association of Criminal Defense Attorneys
  • Los Angeles County Bar Association


In 2021, Baker Marquart became Waymaker. Information on this website reflects results obtained by Baker Marquart. Please click here to learn more about our name change.