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Mary Bonacorsi

Senior Counsel

St. Louis
314 552 6014 314 552 6014 direct

Mary has spent her  40-year career representing major corporations in high-stakes trials and arbitrations.

Mary advises clients on complex disputes of all types, including general commercial litigation defense, real estate and construction claims, labor and employment matters, banking, and railroad real estate.  She has tried, as lead counsel, more than 75 jury and non-jury cases to conclusion and is a member of the American Board of Trial Advocates.

A key player in some of the longest and most complex trials in the St. Louis region, Mary developed excellent relationships with judges and opposing counsel.  She is frequently asked to join pending cases when parties need an experienced courtroom litigator since she excels at leading trial teams, crafting trial strategy, and coordinating the many moving parts of litigation. Mary is a gifted story-teller, supporting her client's cases through skillful cross-examination of opposing witnesses.

Mary was one of the very first women litigators in St. Louis and a founder of Thompson Coburn's Total Commitment® Women's Initiative. In 2015, Mary's role as a mentor and business leader was recognized by the YWCA of Metro St. Louis with a 2015 Leader of Distinction award. She is also a Life Fellow of the American Bar Foundation.

Mary served on the trial team that defended a regional beverage distributor sued after it challenged a 100-year-old state regulation governing relationships between suppliers and distributers. The case, which raised significant questions about state franchise law, was successfully settled a week into a jury trial. (2014)

Mary successfully tried a case for an Illinois school board in a federal jury trial over an age discrimination suit. (2013)

Mary successfully negotiated a settlement that resolved a dozen lawsuits between multiple railroads and the Illinois Department of Transportation over railroad property taken for the construction of the Stan Musial Veterans Memorial Bridge and related highway projects. (2013)

Mary obtained a judgment for a major banking institution that spared it from making multimillion dollar capital contributions to a large apartment development financed through federal historic tax credits. The same ruling also allowed the bank to sell its limited partnership interests without liability for additional contributions or guaranties. (2011)

In a case of national importance, Mary succeeded in obtaining a temporary restraining order for a major regional transit authority in an action to stop collection of a $40 million-plus payment resulting from the downgrade of investment ratings for AIG, which had provided credit support to the transit agency. The action was the lead case in the nation and watched by municipalities in the U.S. and banks around the world that were equity investors in AIG-backed transactions. The aggregate potential liabilities were over$300 million for the transit agency. Prior to a formal ruling, negotiations between both parties resulted in a private settlement. (2008)

Mary prevailed on summary judgment in Cole County in a case brought by the Missouri Attorney General's Office against a railroad client over the railroad's plans to dismantle an abandoned bridge and use the steel for construction of a new bridge. The ruling was affirmed by the Western District Court of Appeals, and Mary also represented the railroad before the Clean Water Commission, which upheld issuance of a DNR permit for the project. (2007)


St. Louis Boys & Girls Club announces plans for youth golf facility at former Superfund site

Missouri Lawyers Weekly honors Mary Bonacorsi as a Women’s Justice Awards winner

Cleaning up a toxic site for the Boys & Girls Club

Mary Bonacorsi named a Leader of Distinction

St. Louis Business Journal covers Thompson Coburn’s work on unique Superfund settlement

EPA, Boys & Girls Club announce $30 million cleanup of Superfund site

Boys & Girls Clubs of Greater St. Louis honors Thompson Coburn for pro bono work on Superfund cleanup site

Women’s Initiative kicks off 2013 mentoring program

Thompson Coburn obtains Missouri Supreme Court victory for Laclede Gas Company