top of page

diana m. geis


PH: 210-226-2182
FAX: 210-226-1691



Diana M. Geis began her legal career as a Briefing Attorney for Paul W. Nye, Chief Justice of the Texas Court of Appeals at Corpus Christi. She has an extensive litigation practice involving diverse areas of substantive law in state and federal courts. These matters include representation of numerous clients in complex business disputes, real estate, fiduciary and probate litigation. She has represented clients in shareholder litigation, disputes between co-owners of businesses, condemnation actions, environmental litigation, and in employment-related litigation. Ms. Geis has also handled complex family law disputes and white collar criminal defense, and has represented creditors in bankruptcy proceedings.


  • St. Mary’s University School of Law (Doctor of Jurisprudence 1983)

  • St. Mary’s Law Journal, 1981-1982

  • The University of Texas at Austin (Bachelor of Arts, 1978)


• State Bar of Texas 

• Texas Trial Lawyers Association 

• San Antonio Bar Association, Director (2007-2009)

• San Antonio Bar Foundation, Fellow 

• Bexar County Women’s Bar Association (2004 President) 

• Phi Delta Phi Legal Fraternity 

• National Association of Women Lawyers

Honors & Distinctions

  • “Texas Super Lawyer” for 2006-2023 by Thomson Reuters, under the category of Business Litigation 

  • Listed by Scene in SA magazine as one of San Antonio’s Best Business Litigation Attorneys (2007-2009)(2011-2019) 

  • Belva Lockwood Outstanding Lawyer Award, Bexar County Women’s Bar Association (2008)

  • “AV” rating (the highest possible) by the Martindale-Hubbell Law Directory

Professional Affiliations

• Bar Association of the Fifth Federal Circuit

• Sustaining Life Fellow of the Texas Bar Foundation

Representative Cases

  • Representing and successfully defending managing partner and representatives in complex partnership litigation.

  • Representing and successfully defending limited partner in partnership derivative action and allegations of fiduciary breaches.

  • Representing and successfully defending majority shareholder in shareholder derivative action and allegation of fiduciary breaches.

  • Representing and successfully defending energy company in environmental, property and personal injury claims.

  • Representing and successfully defending executors and trustees against multiple claims in connection with probate proceedings.

  • Representing and successfully defending state-chartered university against various claims brought by executor in probate proceedings.

  • Representing a client in both civil and criminal antitrust litigation.

bottom of page