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  1. Professionals

John Sullivan

Partner

Dallas

+1 214-453-6498

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  • Overview
  • Experience
  • Credentials
  • Insights & News

John is a trial lawyer with significant courtroom experience in both federal and state courts as well as arbitrations. His practice focuses on complex commercial litigation for corporations and individuals across a wide variety of industries, as well as internal investigations and white collar criminal defense.

John represents clients at all stages of litigation and has extensive dispositive motion, deposition, oral argument, and trial experience, and works closely with witnesses to prepare them for deposition and trial testimony. John has served as a key member of multiple trial teams, including second chair experience, making an opening statement, and examining witnesses. John frequently represents clients in matters involving breach of contract, fraud, trade secrets, fiduciary duties, the False Claims Act, class actions, and other business disputes and regulatory matters. His experience also includes obtaining injunctive relief, providing pre-litigation and regulatory counseling, engaging in alternative dispute resolution proceedings, and obtaining favorable settlements.

John was previously selected to serve as an Assistant District Attorney at the Dallas County District Attorneys’ Office through its lawyer on loan program where he tried multiple criminal jury trials to verdict, handling everything from voir dire through closing argument. John maintains an active pro bono practice with a variety of commercial and civil rights matters, and during law school served as an intern to the Honorable Robert E. Gerber, United States Bankruptcy Judge for the Southern District of New York.

Key Matters

John’s representative experience includes the following:

      • Defended three major financial institutions against False Claims Act allegations, obtaining dismissal in the District Court, which was upheld on appeal.
      • Represented a technology company in a dispute involving alleged breaches of contract, fraud, tortious interference, unfair competition, and trade secret misappropriation.
      • Represented a defense contractor in a confidential internal investigation.
      • Represented an oil and gas company in a dispute involving a wild well incident.
      • Represented two qui tam Relators in a False Claims Act case for which a favorable settlement was obtained.
      • Represented a business in bringing claims relating to departing employees.
      • Represented a consulting company in a dispute involving allegations of trade secret misappropriation.
      • Represented a financial institution in a case involving a breach of contract.
      • Represented various businesses and individuals in disputes involving allegations of breach of contract and fraud.
      • Represented international construction companies in a dispute involving alleged fraudulent transfers and breach of fiduciary duties.
      • Represented an individual in a confidential dispute and obtained a complete dismissal on jurisdictional grounds.
      • Obtained a temporary restraining order for a small business in a real estate dispute.
Recent Experience
ProFrac Holdings II, LLC, Acquires Monarch Silica, LLC

  • Best Lawyers: Ones to Watch® in America
    • Commercial Litigation (2023-2025)
    • Criminal Defense: White Collar (2024-2025)

John is a member of the Dallas Association of Young Lawyers and maintains an active pro bono practice, having litigated various civil rights and consumer matters.

Capabilities

Commercial Litigation & Disputes
Litigation/Trials
Government Program Fraud, False Claims Act & Qui Tam Litigation
White Collar & Government Investigations
Privacy & Data Security
Securities, M&A & Corporate Governance Litigation
Energy
Energy Industry Litigation & Investigations
Oil & Gas

Key Matters

John’s representative experience includes the following:

      • Defended three major financial institutions against False Claims Act allegations, obtaining dismissal in the District Court, which was upheld on appeal.
      • Represented a technology company in a dispute involving alleged breaches of contract, fraud, tortious interference, unfair competition, and trade secret misappropriation.
      • Represented a defense contractor in a confidential internal investigation.
      • Represented an oil and gas company in a dispute involving a wild well incident.
      • Represented two qui tam Relators in a False Claims Act case for which a favorable settlement was obtained.
      • Represented a business in bringing claims relating to departing employees.
      • Represented a consulting company in a dispute involving allegations of trade secret misappropriation.
      • Represented a financial institution in a case involving a breach of contract.
      • Represented various businesses and individuals in disputes involving allegations of breach of contract and fraud.
      • Represented international construction companies in a dispute involving alleged fraudulent transfers and breach of fiduciary duties.
      • Represented an individual in a confidential dispute and obtained a complete dismissal on jurisdictional grounds.
      • Obtained a temporary restraining order for a small business in a real estate dispute.
Recent Experience
ProFrac Holdings II, LLC, Acquires Monarch Silica, LLC

Credentials

Education

John received a J.D. in 2015 from the University of Pennsylvania. While at Penn Law, he was an executive editor for the Journal of Business Law and received a Certificate in Management from the Wharton School. He received his B.A., magna cum laude, in philosophy and political science in 2012 from the University of Notre Dame, where he was inducted into Phi Beta Kappa.

During law school, John interned for the Honorable Robert E. Gerber of the United States Bankruptcy Court for the Southern District of New York. 

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    Capabilities

    Commercial Litigation & Disputes
    Litigation/Trials
    Government Program Fraud, False Claims Act & Qui Tam Litigation
    White Collar & Government Investigations
    Privacy & Data Security
    Securities, M&A & Corporate Governance Litigation
    Energy
    Energy Industry Litigation & Investigations
    Oil & Gas
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