About the Firm


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Our Practice

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Our Attorneys

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About the Firm


The firm was founded in 2003 and has offices in the financial district of downtown San Diego. Its shareholder, Audie de Castro, previously worked for a larger corporate law firm. He founded his own firm so that he could offer much more personalized services at reasonable rates. We have a business approach to practicing law. We learn our clients’ businesses and listen to their needs. Our focus on the specific needs of clients helps us achieve legal and business success for them cost-effectively. That is why we have been retained to represent private and publicly traded companies, domestic and international. We have represented clients in the United States and other countries, including Canada, China, Germany, the Philippines and the UK. Audie de Castro is the Philippine Honorary Consul of San Diego.

We have represented domestic and international clients on a regular basis over many years. We advise them on day-to-day business matters as corporate counsel. We have successfully negotiated and closed complex, multi-million dollar deals. Some of our key business practice areas include corporate governance, limited liability company laws, securities offerings and compliance, mergers & acquisitions, commercial real estate, licensing and distributorships, and business agreements.

Our clients trust us to represent them when they are involved in major disputes, no matter the opponent. We have successfully handled contentious and high stakes litigation in state and federal courts, including cases involving breach of contract, breach of fiduciary duty, shareholder and partnership disputes and arbitration, fraud, securities, franchise, real estate, and other commercial disputes. We advise our clients to be practical about resolving disputes. But we will vigorously litigate disputes when it makes business sense to do so, including going to trial.

Our Practice


We are a full-service business and civil law firm. We successfully handle both transactional and litigation matters for businesses, entrepreneurs, investors, and individuals.
We practice in the following areas:




  • Breach of Contract
  • Fraud
  • Breach of Fiduciary Duty
  • Corporate Governance
  • Shareholder and Partnership Disputes
  • Franchise Disputes
  • Real Estate Disputes
  • Securities
  • Employment
  • Negligence




  • Contract Review
  • Entity Structuring and Formation,
    including Corporations, LLCs and LPs.
  • Corporate Governance
  • Securities Offerings, Public and Private
  • Securities compliance
  • Rule 144 transactions
  • Mergers & Acquisitions
  • Commercial Loan Financing
  • Commercial Real Estate Acquisition and Leasing
  • Licensing and Distributorships



Our Team


Audie J. de Castro, Shareholder


Audie de Castro practices in business litigation and transactional law. He has extensive litigation experience in litigating business, corporate, employment, real estate and investment matters, including fraud or misrepresentation, breach of fiduciary duty, securities, franchise disputes, accounting, and breach of contract claims. His clients include companies in biotech, manufacturing, real estate, services, hospitality, and health care.

He has achieved significant success at various levels, from obtaining large settlements to winning trials. In 2023, he won $20 million in a federal lawsuit for breach of fiduciary duty, fraud and securities law violations. In 2022, he represented voters in enforcing the Voting Rights Act against the City of National City, resulting in the City transitioning its election system from at-large voting to district voting for the first time in its history. Mr. de Castro has received recognition as a Super Lawyer (Business Litigation) by Super Lawyer Magazine in 2021, 2022, 2023, and 2024.

In his transactional practice, he has closed complex and large transactions, such as mergers and acquisitions, securities offerings, franchising, licensing, distributorships, and commercial real estate deals. He has represented public and private companies, investors and entrepreneurs.

He is also General Counsel for several companies, including OpSam Health, a federally qualified health center, and San Diego Workforce Partnership, the local workforce development board.

Mr. de Castro graduated cum laude from the University of San Francisco School of Law. He was a senior staff member of the University of San Francisco Law Review and McAuliffe Honor Society (top 10%). He is admitted to practice in all California state courts, the U.S. District Courts in the Northern, Southern and Central Districts, and the 9th Circuit Court of Appeals. He received a business degree from the University of San Diego and obtained a CPA license (inactive).

He is a member of the San Diego County Bar Association, the American Bar Association and the American Health Lawyers Association. Mr. de Castro previously taught Business Associations at Thomas Jefferson School of Law.

Since 2014, Mr. de Castro has served as the official government representative of the Republic of the Philippines, for San Diego County. He is the country’s Honorary Consul and overseas a jurisdiction of over 200,000 constituents.

Mr. de Castro is also a leader in civic affairs. He previously served on the Board of Governors for the San Diego Foundation. He is also past President of the Asian Business Association of San Diego and the Filipino-American Lawyers of San Diego. He is a graduate of LEAD San Diego (2003).

He enjoys spending time with his wife and two boys, exercising, and cooking.  He speaks Tagalog and English. 



Jonathan J. Elia, Attorney


Jonathan practices business litigation and represents both individuals and businesses in their various legal needs. He began his legal career in one of California’s largest workers’ compensation defense firms. He then joined a plaintiff’s personal injury firm, before making his way to business litigation. Jonathan’s varied legal experience allows him to assist clients with their legal needs beyond business litigation.

Jonathan received his B.A. in Criminal Justice from San Diego State University in 2015 and received his Juris Doctorate from the University of San Diego in 2018 with a concentration on business and corporate law. He passed the bar in 2018, is admitted to practice in all California state courts, the U.S. Southern District Court, and is a member of the San Diego County Bar Association. He also speaks Romanian.

He spends his free time, traveling, trying new foods, and watching e-sports with friends


John R. Mayer, Of Counsel


John represents businesses and individuals in their various legal needs, including litigation, corporate and transactional work, real estate matters, employment-related issues, and class action defense. Having worked as general counsel for two companies, John brings a business world practicality to his practice of law.

John received his B.A. from the University of California, Santa Barbara in 1994 and graduated cum laude from Thomas Jefferson School of Law in 1998, where he was a member of the Thomas Jefferson Law Review. After passing the California bar exam, he practiced with the mid-sized law firm Hayes Simpson Greene LLP until late 2001, when he started his own practice. Since then, he has practiced with a partner and as a solo practitioner, and he established John R. Mayer, A Professional Law Corporation in 2005.

John has been active in the community for many years, having served as president and a board member of San Diego Teen Court, a non-profit peer sentencing program for first-time juvenile offenders, and on the board of directors for Outdoor Education Foundation, a non-profit fundraiser for Sixth Grade Camp at Cuyamaca. John is also a licensed California real estate broker.

John is married, to wife Vanessa, and they have two young boys (Jordan and Nash).


Matthew Erickson, Of Counsel


Matthew is a highly skilled civil litigation attorney with a strong educational background and a commitment to delivering exceptional legal services to clients in transactional, pre-litigation and litigated matters. He is admitted to practice before all courts in the State of California as well as federal district courts in California. He prides himself on having an extremely diverse set of skills and adeptness navigating complex legal matters. His primary focus at the firm is employment and business litigation. He has worked on over 500 employment law cases in his career, representing both plaintiffs and defendants.

Prior to receiving his J.D. and Certificate in Dispute Resolution from Pepperdine School of Law, Matthew earned his Bachelor’s degree in History from UCLA with College Honors and Departmental Highest Honors.

While pursuing his undergraduate education, Matthew worked full-time in a busy employment law practice. Just two years into his legal career, Matthew became the firm’s office manager. Since being admitted to the California Bar in 2013, Matthew has maintained a solo practice.

With an unwavering dedication to his clients’ best interests, Matthew has amassed extensive experience in employment, business and civil litigation. He has successfully represented individuals, businesses, and organizations in a wide range of civil matters.

Matthew's approach is characterized by meticulous preparation, attention to detail, and strategic advocacy. He has a proven track record of achieving favorable outcomes for his clients.

When Matthew is not working, he primarily enjoys spending time with family, watching movies, and going to thrift stores and auctions.


Kateryna Borge


Ms. Borge is a multilingual translator and interpreter. Fluent in four languages, she speaks Russian, Ukrainian, English and French. She graduated from Kyiv National Linguistic University and received a certification from the University of Geneva and a private French school in Nice, France. She is a member of American Translators Association and Association of Translators & Interpreters in the San Diego area. Participated in Model United Nations and European Youth Parliament sessions.

Ms. Borge has a background in law, business and finance and is the firm’s paralegal. Prior to joining the firm, Ms. Borge held a legal internship in the San Diego Superior Court and worked in a personal injury law firm. She is a member of the San Diego Paralegal Association. Ms. Borge is a volunteer translator and interpreter for a local non-profit law center that provides services to victims of human and civil rights violations and is a Special Recognition Awardee of the 2022 La Mancha Awards. With her strong international background, she also handles consular matters for the Philippine Consulate, San Diego.

In her free time, Ms. Borge enjoys reading, hiking and photography.


Contact Information


We are centrally located within the financial district of downtown San Diego. We are on the 17th floor of the Bank of America Building. Our offices are within walking distance of Federal and State courthouses. Our contact information is below: 701 B Street, Suite 1745
San Diego, California 92101
Phone: (619) 702-8690
Facsimile:(619) 702-9401

If you wish to contact us, please email us at adecastro@decastropc.com and we will respond to you shortly. If this is an urgent matter, please call us directly at (619) 702-8690.