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Photo of Peter J. Diedrich

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 construction, as well as commercial and labor and employment litigation. Mr. Diedrich also has substantial experience in cases involving director and officer liability, corporate governance and control, unfair competition, and complex contract issues.

His practice currently focuses on representing employers in a broad range of employment areas, including wrongful termination, discrimination, harassment, retaliation, failure to accommodate claims, breach of contract claims, and wage and hour claims, including the defense of class actions and PAGA actions.

Mr. Diedrich actively participates in all aspects of these cases before state and federal courts, arbitration, and administrative agencies. He also advises employers on how to comply with state and federal laws, and provides employment counseling on disciplinary matters, terminations, layoffs, leaves of absences, disability issues, investigations of internal complaints, and severance agreements.

Recently, Mr. Diedrich prevailed on summary judgment in an age and gender discrimination action, and then prevailed on appeal in the same matter (Aghili v. El Clasificado, 2d Dist. Ct. of Appeal case no. B292526.)

Throughout his career, companies in various industries have also turned to Mr. Diedrich for assistance on a variety of significant commercial 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 is affiliated with and has sat 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.

Admissions & Associations

State Bar of California

Los Angeles County Bar Association, Member

American Bar Association, Member

Practice Groups

Georgetown University Law School, J.D.

University of California, San Diego, B.A.
magna cum laude

Awards & Recognitions