Dan O’Toole, a respected leader and trial strategist, is a key member of Armstrong Teasdale’s Litigation practice group and serves as chair of the Employment and Labor practice area.

In his practice, Dan defends employers against a broad range of complaints and threats of legal action involving workplace situations. Because of his background and achievements in employment and labor law, Dan has been recognized repeatedly by Chambers USAThe Best Lawyers in AmericaSuper Lawyers and for the last several years was included as one of the “Top 50” lawyers in the St. Louis area. In addition, The Best Lawyers in America named him 2018 Lawyer of the Year in Employment Law.

His experience includes numerous trials and arguments before state and federal courts and administrative tribunals, including the Equal Employment Opportunity Commission, the Missouri Human Rights Commission and the U.S. Department of Labor.

The matters he handles include allegations of discrimination and wrongful termination under the Family and Medical Leave Act, Title VII of the Civil Rights Act, the Americans with Disabilities Act, the Age Discrimination in Employment Act, the Missouri Human Rights Act and other state and federal laws. This work encompasses the defense of employers against retaliation and whistleblower claims and other wrongful discharge allegations. In another area of employment law, Dan provides counsel on cases alleging the disclosure of trade secrets and violations of noncompete agreements.

Outside of the courtroom, Dan helps clients take steps to avoid costly lawsuits involving such personnel matters as workforce reductions, restructuring and compliance. His insights into the complex and rapidly changing world of employment and labor relations prepare clients to make sound business decisions in the alleviation, prevention and resolution of conflicts. Dan also drafts, reviews and improves policies, handbooks and employment contracts.

A dynamic, engaging and often humorous speaker, Dan is frequently invited to present training seminars on such employment law issues as supervisory duties, interviewing and screening job applicants, sexual harassment prevention and investigation and EEOC policies and procedures, and proper termination practices.

In his administrative position at Armstrong Teasdale, Dan plays an instrumental role in developing the firm’s strategy for current and long-term growth. He is also a member of the firm’s Contingent Fee Committee.


  • University of Missouri School of Law  (J.D., 1990)
    • Journal of Dispute Resolution, Volume 1990 (Lead Articles Editor)
  • Southwest Missouri State University  (B.A., 1987)


  • Missouri, 1990
  • Illinois, 1991
  • Arkansas
  • U.S. District Court, Eastern District of Missouri
  • U.S. District Court, Western District of Missouri
  • U.S. District Court, Southern District of Illinois
  • U.S. District Court, Eastern District of Arkansas
  • U.S. District Court, Western District of Arkansas

Professional Activities

  • The Missouri Bar
  • American Bar Association 
  • Armstrong Teasdale Executive Committee

Charitable and Civic Involvement

  • Ronald McDonald House Charities of Metro St. Louis (Human Resources Committee) 


  • The Best Lawyers in America®; Labor and Employment Litigation, Employment Law—Management, Qui Tam Law (2008-present); Lawyer of the Year, Employment Law—Management (2016, 2018); Lawyer of the Year, Labor and Employment Litigation (2020)
  • Selected as a 2013 Top Rated Lawyer in Labor & Employment by Martindale-Hubbell and American Lawyer Media (ALM)
  • Missouri/Kansas Super Lawyers® (2008-present); Super Lawyers®, Business Edition (2011-present); Super Lawyers®, Top 100 Missouri & Kansas (2010-2013); Super Lawyers®, Top 50 St. Louis (2010-present)
  • Chambers USA: America's Leading Lawyers for Business for Labor and Employment Law, Band 1 (multiple years)
  • AV® Peer Review Rated, Martindale-Hubbell