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Gary J. Siller

fax +1 832.397.3512

Gary J. Siller represents clients in healthcare, general business disputes, fiduciary claims, accounting malpractice, tax controversy, and energy.

Gary maintains a domestic and international business litigation practice, serving as a legal advisor on litigation and non-litigation matters alike. A Board Certified Trial Attorney, Gary applies his business and financial experience to find solutions to client problems. Gary practiced as a CPA before attending law school and has founded and operated three successful businesses. Based on this experience, he understands how businesses must be managed as well as the challenges they confront. Gary views situations from the business client’s perspective and is adept at quickly sorting through issues and formulating a strategy.

Gary’s current litigation practice focuses on healthcare, general business disputes, fiduciary claims, accounting malpractice, tax controversy, and energy. He represents clients in state and federal courts and in arbitrations across Texas as well as representing clients in international arbitrations before the International Court of Commerce. He also serves as outside General Counsel for two clients, acting as the initial gatekeeper for all legal matters and as a member of each client’s advisory team.

Healthcare clients turn to Gary for guidance on a variety of important matters. For example, he represents durable medical equipment providers (DMEs) and other providers on claims against the Texas Department of Health and Human Services (HHSC) and against Managed Care Organizations (MCOs). Such representations generally concern Medicaid reimbursement, violations of the Texas Insurance Code and healthcare regulations, retaliation by an MCO and breaches of MCO/provider agreements. Gary deals directly with HHSC regarding the issuance of clarifications of existing regulations and/or the promulgation new regulations. Gary represents medical providers in payor disputes against insurance companies and represents clients in the defense of claims by the federal and state offices of the Inspector General related to issues of reimbursement and audits. Finally, Gary also represents medical products manufacturers and distributors in a variety of matters.

Both individuals and companies seek Gary’s representation in shareholder disputes, wrongful terminations, employee theft, and all types of business litigation and adversarial proceedings. He is frequently involved in temporary restraining order proceedings (TROs) and temporary injunctions (TIs). Gary also represents individuals and companies in claims related to fiduciary litigation such as disputes between siblings related to the family business, matters related to the administration of an estate, claims against broker/dealers for security violations and other related matters.

When accounts need representation in accounting malpractice cases, they need an attorney with a long history of experience. Gary has successfully defended more than 70 accounting malpractice cases in a broad range of disputes including matters related to audits, reviews, compilations, special engagements, tax matters, and securities claims.

Companies and individuals facing tax audits as well as matters before the IRS and in Federal Tax Court seek reliable, experienced counsel. Gary’s tax controversy practice includes disputes involving federal income tax, sales tax, trust fund recovery penalties, independent contractor vs. employee, innocent spouse and the reporting of foreign assets in various other related tax matters.

Gary’s representation of his South American clientele, particularly from Venezuela, comprises a significant portion of his practice, including representation in litigation and non-litigation matters. This representation includes domestic and international contract disputes, corporate structuring, general tax advice, due diligence investigations and contract negotiations. Gary has been active in assisting clients in a variety of international dealings including the creation of entities all over the world. Gary has handled matters in Aruba, the British Virgin Islands, Canada, Curacao, China, Germany, Holland, Mexico, Panama, Portugal, Spain, Switzerland, and various other countries.

He also maintains a significant South American clientele, which he represents in both litigation and non-litigation matters. This representation includes the handling of a variety of general corporate matters as well as providing general tax (domestic and international) advice, due diligence, and the handling of negotiations in a variety of circumstances. Gary has been active in assisting clients in a variety of international dealings including the creation of entities all over the world.

Gary also occasionally represents celebrities, including professional athletes.

Gary Siller is Board Certified in Personal Injury Trial Law by the Texas Board of Legal Specialization. He is also a Certified Public Accountant in the State of Texas.


J.D., cum laude, University of Houston Law Center, Houston, Texas, 1984, Order of the Coif; Order of the Barons; Houston Law Review, Associate Editor, 1983-84
B.B.A., with Honors, The University of Texas at Austin, Austin, Texas, 1981, Graduated in the top 1% from School of Business


Rated AV Preeminent by Martindale-Hubble


Houston Bar Association

Texas Society of Certified Public Accountants

Houston CPA Society, Board of Directors, Healthcare Committee

National Association of Corporate Directors

Turnaround Management Association

American Diabetes Association, Board of Directors

Ducks Unlimited, Life Sponsor

President of Galveston Crash Boat Basin Homeowners Association

State Bar Licenses


Court Admissions

U.S. District Ct., S.D. of Texas
Supreme Court of Texas
  • Defended a large E&P company in a four week trial involving both a death and personal injury in South Texas.
  • Successfully represented a mid-size accounting firm in a month-long trial on claims alleging accounting malpractice brought by an investment banking firm and individual investors on an alleged failed audit.
  • Defended a claim in excess of $75 million against an insurance brokerage firm. Gary managed a team of five lawyers defending this claim.
  • Defended a publicly traded company involved in a Sarbanes-Oxley whistleblower complaint.
  • Represented a large medical products distributor in a claim before the state office of the Inspector General.
  • Represented a large DME provider in AAA arbitration against a large MCO related to claims of retaliation and breach of the MCO’s/Provider contract.
  • Represented a DME against HHSC related to proper reimbursement for various Medicaid products and services, and failure to clarify wording of various regulations.
  • Represented an ex-NBA basketball star in his dispute with the National Basketball Association and the Dallas Mavericks.
  • Represented a Houston Texans football player in his lawsuit against the City of Houston involving a taser incident.