Deborah S. Mallgrave

Direct: (949) 383-2790
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Orange County

650 Town Center Drive
Suite 1700
Costa Mesa, CA 92626
Main: (949) 383-2800

Deborah Mallgrave concentrates her practice on business litigation and class actions, intellectual property disputes, and trust litigation.  She represents both large and small businesses, as well as private individuals, in complex disputes involving business transactions and contracts, fraud, unfair competition, shareholder and partnership disputes, real estate, and other business matters.  Additionally, she represents clients in matters involving various intellectual property disputes, including trademark, trade secret, and patent claims.  Ms. Mallgrave appears in state and federal courts throughout the state and nation, as well as arbitration and mediation proceedings.  Ms. Mallgrave also has extensive e-discovery experience, having managed the collection and review of complex discovery databases, and preparation of efficient and time-saving review protocols.

Representative Matters

  • Defended educational institution in trademark infringement lawsuit where alleged damages were estimated to exceed $60 million. Obtained a favorable settlement after successfully defending a four day preliminary injunction evidentiary hearing.
  • Defended national retailers and merchandising company in multiple trademark infringement suits involving production and sale of merchandise using language similar to that in viral internet video, negotiating settlement for a fraction of claims.
  • Defended industry leader in baby products against multiple patent infringement lawsuits, obtaining favorable settlements and, in one case, prevailing on summary judgment and successfully invalidating the patent at issue.
  • Represented global leader in design and manufacture of heart valves in multiple patent infringement litigations, including mock trial and jury research projects.
  • Represented solar panel manufacturer in multiple patent infringement lawsuits against competing company, negotiating settlement agreement involving confidential business provisions.
  • Trial counsel for water park attraction company in action to compel former employee to assign patents and to correct inventorship, resulting in favorable decision following trial.
  • Trial counsel for defendants in two and half month jury trial involving claims for breach of contract and fraud arising out of purchase of semiconductor products from one of world’s largest semiconductor manufacturers. Defendants cross-claimed for damages, and jury found for defendants and rendered a seven-figure verdict in defendants’ favor. 
  • Trial counsel for defendants in two month jury retrial following reversal on appeal involving breach of contract and fraud lawsuit to enforce real estate partnership, successfully reducing damage award from 80% of claimed partnership property to 15%.
  • Successfully defended individual owners and employees of import company in two week jury trial against fraud claims.
  • Prosecution of contract and fraud claims to enforce contract to design power supply for video displays against one of world’s largest television manufacturers, obtaining awards for discovery sanctions and ultimately settling on favorable terms.
  • Defended class actions brought against international clothing manufacturer for violation of consumer trade practices and unfair competition laws in multiple states, including development and implementation of refund program involving millions of consumers and millions of dollars.
  • Defended school district consultant and retirement plan administrator in class action by public school employees claiming defects in supplemental retirement plan, negotiating class-wide settlement on favorable basis.
  • Defended leading motor vehicle manufacturer in dispute arising from dealer termination, obtained stipulated dismissal with prejudice with no recovery by plaintiff.
  • Represented defendant in litigation to obtain support and property based on parties’ 19-year cohabitation, obtaining a favorable settlement.
  • Representation of defendants in shareholder dispute, successfully vacating prejudicial arbitration award ousting clients from control of company and disqualifying arbitrator in multi-jurisdictional dispute.
  • Defense of breach of contract, fraud, and breach of fiduciary claims brought against national title company in connection with fraudulent loan scheme by loan originators, settling on favorable terms.
  • Represented defendant in arbitration involving purchase of real property, resulting in negotiation and execution of settlement requiring immediate sale and transfer of property within 24 hours.
  • Trial counsel for shareholder in bench trial over shareholder dispute, involving breach of fiduciary claims, usurping of corporate opportunities, and dissolution.
  • Successfully defended corporate trustee against breach of trust, fiduciary, and elder abuse claims relating to trust administration and alleged modification of trust, settled with no recovery against trustee, and affirmatively recovered attorneys’ fees and additional compensation for trustee.
  • Prosecution of trust litigation against trustee for breach of fiduciary duty and conflicts of interest involving trust with assets worth approximately $60 million.
  • Lead litigator assisting client with trust administration and workout of claims against trust, including emergency loan financing for business owned by trust.
  • Represented successor co-trustee to trust in trust litigation and elder abuse litigation involving issues of incapacity and undue influence of trustor.

Awards & Recognitions

  • Wiley W. Manuel Certificate for Pro Bono Legal Service, State Bar of California (2006, 2009-2015)
  • Attorney of the Year, Public Law Center (2009)

Professional & Community Activities

  • Public Law Center
    • Board of Directors (2013-2015)
    • Executive Board of Directors (2016-present)
      • Vice President (2019)
      • Secretary/Treasurer (2018)
  • Federal Bar Association, OC Chapter, Board of Directors
  • State Bar of California
    • Litigation Section
    • Business Law Section
    • Intellectual Property Law Section
  • Orange County Bar Association
  • Association of Business Trial Lawyers

Publications & Lectures

  • The Hidden Benefits of Pro Bono
    Fall 2013 | Author, ABA Woman Advocate Newsletter, Vol. 19, No. 1
  • Addressing Conflicts of Interest as In-House Counsel
    October 10, 2013 | Speaker, Snell & Wilmer and Thomson Reuters Harbor Cruise, Newport Beach, CA
  • Hidden Pitfalls in Commonly Negotiated Provisions in Key Business Documents
    June 15, 2016 | Co-Presenter, Association of Corporate Counsel (Southern California Chapter), Long Beach, CA
  • Pitfalls for Family Trustees
    October 1, 2018 | Orange County Business Journal

In the News

  • Greenberg Gross Announces New Partner Deborah Mallgrave
    June 3, 2019 | Press Release | Read Article


J.D., magna cum laude, Vermont Law School, 1998

  • Managing Editor, Vermont Law Review
  • Dean’s Fellow

B.A., University of California, Santa Barbara (Economics and Environmental Studies), 1994


  • State of California
  • U.S. Court of Appeals for the Ninth Circuit
  • U.S. Court of Appeals for the Federal Circuit
  • U.S. District Court for the Central District of California
  • U.S. District Court for the Eastern District of California
  • U.S. District Court for the Northern District of California
  • U.S. District Court for the Southern District of California

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