Kathleen R. Hartnett


Kathleen Hartnett is an experienced trial and appellate lawyer who represents plaintiffs and defendants in high-stakes civil litigation, investigates business-sensitive matters and provides strategic counseling. Her practice spans commercial, regulatory and constitutional matters, including serving as counsel to leading global technology companies in high-stakes commercial and class action litigation. She has also counseled, investigated and litigated founder disputes and employment issues. Kathleen has worked closely with industry and government leaders facing complex challenges involving litigation, policy and politics. She also has significant pro bono and public-oriented litigation experience. In all of her representations, Kathleen brings a deep concern for the client and the client’s objectives – and the tireless effort needed to achieve those objectives.

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  • Cooley Files Second Amicus Brief in Texas Illegal Voting Case 

  • Cooley Files Amicus Brief Supporting Website Platform Immunity in Section 230 Case 

  • Cooley Files Amicus Brief in Reproductive Rights Case Before SCOTUS 

  • Cooley + League of Women Voters File Amicus Brief in Second Amendment Case Before SCOTUS to Protect Electoral Process and Right to Vote Safely 

  • Cooley + Coalition Sue West Virginia to Challenge Law Discriminating Against Transgender Youth 


  • Harvard Law School
    JD, magna cum laude

  • Harvard College
    AB, Government
    magna cum laude

Admissions & Credentials


District of Columbia

New York