For more than a century, Armstrong Teasdale LLP has forged long-term relationships with clients large and small around the globe.

We have a long and distinguished track record of delivering sophisticated legal advice and exceptional service in nearly every area of law. With offices across the U.S. and in the U.K., Armstrong Teasdale is perfectly positioned to provide Lex Mundi member firms and clients innovative legal services. Our attorneys work together to guide clients through virtually every challenge, from day-to-day operational decisions to some of the most complex legal matters.

With hundreds of multidisciplinary attorneys working across practice areas and industry teams, our firm has the ability to provide services of scale, encompassing both traditional and niche fields such as agribusiness and food, complex commercial litigation, manufacturing, technology, public finance and municipal law, fire and electrical liability, health care and life sciences, higher education, noncompete and trade secrets, security clearance and privacy and data security.

The firm and its attorneys are fortunate to have garnered national and global recognition across services areas, as well as for the firm’s culture and commitment to diversity, equity and inclusion.

Ranked among the AmLaw 200, Armstrong Teasdale serves a broad client base including multinational and Fortune 500 companies. We also leverage a number of subsidiaries and industry affiliations, including with AT Government Strategies, which provides government relations and strategic counsel to advance the business objectives of companies, industry associations and other entities; and Lawgical Choice, which uses advanced technology to organize and present relevant case information in a targeted, trial-ready format.


  • Received dozens of first-tier metropolitan rankings in the 2021 edition of the U.S. News & World Report and Best Lawyers list of “Best Law Firms.”
  • The 2020 edition of Chambers ranked 20 Armstrong Teasdale attorneys as leading lawyers in their respective practice areas.
  • Received the highest possible score on the 2021 Corporate Equality Index, a national benchmarking survey and report on corporate policies and practices related to lesbian, gay, bisexual and transgender workplace equality. The survey is administered by the Human Rights Campaign Foundation, an arm of the largest LGBT civil rights organization in the United States.
  • Ranked by Legal 500 U.K. 2021 as a leading U.K. firm in seven London practice areas.
  • Earned a 2020 BTI Client Service A-Team award as a standout in investing in client relationships and in client-facing communications.