Peter J. Diedrich

Partner, Los Angeles Office


Peter J. Diedrich is a partner in the Firm's Los Angeles office, practicing in the area of complex civil litigation with an emphasis on health care, as well as commercial and real estate litigation.  Mr. Diedrich also has substantial experience in cases involving director and officer liability, corporate governance and control, unfair competition and complex contract issues.

A large portion of Mr. Diedrich’s healthcare experience involves representing health plans in contract disputes. This includes successfully representing a large health plan in an arbitration battle with several dermatology centers in a dispute over $2 million. He has successfully represented two large health plans in a variety of litigation matters for over a decade.

With years of experience representing large corporations in various arbitration forums, companies turn to Mr. Diedrich when involved in high-stakes ADR matters. He successfully defended an Orange County-based apparel manufacturer in a shareholder dispute among its three founding shareholders, which also involved representing the company in state and federal court. He assisted in an investigation and defense of corporate officers and directors of a biotechnology R&D company accused of mismanagement and self-dealing. His team ultimately obtained net recovery in arbitration of approximately $10 million.

Throughout his career, companies in various industries have turned to Mr. Diedrich for assistance on significant litigation matters. Below is a sample of his experience:

  • Committee for Precious Metals and Gems v. Golden ADA, Inc. (USDC, N.D. Cal.) –As part of a team, prosecuted civil RICO action on behalf of an agency of the Russian government, seeking to locate and recover $170 million in gold, diamonds and other valuables sent from Russia to San Francisco and then misappropriated. Ultimately recovered approximately $100 million.
  • Aetna Fraud Cases (Orange County Superior Court, Complex Division) – Investigated, filed and prosecuted six cases on behalf of Aetna’s health plan division against approximately 37 physicians and outpatient surgery centers that were making illegal payments to patients to have unnecessary surgical procedures. This scheme was profiled on ABC’s “Prime Time” news program. In addition, he assisted both the Orange County District Attorney’s Office and the U.S. Attorney’s Office in assembling facts necessary to indict and prosecute approximately six criminal cases arising out of the same scheme. These cases resulted in over a dozen felony convictions and the issuance of more than $3 million in criminal restitution orders.
  • Mosakowski-Lindsey Associates v. Dynasty Plaza Holding, LLC (L.A. Superior Court) – Defended shopping center developer against breach of contract and mechanic’s lien claims brought by project’s former architect. Succeeded in having $2.8 million mechanic’s lien expunged by motion.
  • Downey Regional Medical Center v. Blue Shield of California (L.A. Superior Court) – Defended Blue Shield against claims of unfair competition in connection with the development of a “Medicare Plus Choice” product.
  • Brea Community Hospital v. Blue Shield of California (L.A. Superior Court) – Defended Blue Shield against various claims of improper reimbursement brought by financially troubled hospital.
  • Rhode v. Federal Cartridge Co. (L.A. Superior Court) – As part of a team, represented Olympic gold medalist in action for unauthorized use of name and likeness in advertising campaign.
  • J.D. Uni-Tec v. A.S. Naidu, et al. (L.A. Superior Court) – With co-counsel, defended manufacturer of nutritional supplements against claims for sales commission predicated upon alleged oral contract. Mock jury rated his performance as 3:45 on a scale of 5, which the jury consultant described as “exceptional and rare."

While attending law school, Mr. Diedrich was a staff member and editor of the journal Law and Policy in International Business.


Mr. Diedrich has been selected as Southern California “Super Lawyer” each year from 2005 through 2008 by Los Angeles Magazine.


Mr. Diedrich sits on the Board of Directors of the Boys and Girls Aid Society of Los Angeles County, better known as “Five Acres.”  Five Acres is a leading child and family services organization that promotes safety, well-being and permanent homes for children and their families. Founded as an orphanage in 1888, today Five Acres offers an array of services including residential care and education, a non-public WASC accredited therapeutic school, mental health services in homes and schools, foster care and adoptions, and domestic violence prevention.


  • State Bar of California
  • Los Angeles County Bar Association, Member
  • American Bar Association, Member