Korein Tillery’s attorney roster is just 25 strong, but this St. Louis-based firm has racked up an impressive list of wins during the past year. Perhaps the most surprising victory came in the form of a $105 million settlement with Swiss agribusiness giant Syngenta A.G. on behalf of more than 1,000 water systems around the country where the company’s widely used herbicide atrazine turned up.

The chemical, which has been around since the 1950s and often is used to kill weeds in corn and sugarcane fields, has been linked to several forms of cancer and birth defects.

Success in the case, filed in 2004 by name partner Stephen Tillery, was far from guaranteed. Similar litigation had already failed; no plaintiffs had ever convinced a court that the United States held jurisdiction over Syngenta; and the amount of atrazine detected fell below the maximum level allowed by the U.S. Environmental Protection Agency.

Korein Tillery attorneys spent seven years in discovery, delving into approximately 10 million documents, interviewing more than 30 experts and deposing Syngenta employees in Switzerland.

“We said, ‘The amount doesn’t matter,’ ” said Tillery, who worked with attorneys from Baron & Budd on the case. “If atrazine is in your water, it’s bad no matter the level.”

The team won an important jurisdictional battle after Korein Tillery attorneys argued that two of the Swiss company’s principals served on the board of directors of a U.S. subsidiary. The preliminary settlement was announced in May, less than a year after the court ruled that it held jurisdiction over Syngenta.

Korein Tillery is in the midst of representing the National Credit Union Administration — an independent federal agency tasked with monitoring federal credit unions — in securities litigation against a number of banks. The suits, filed in Kansas and California, claim that the banks misled several now-­defunct credit unions about the quality of bonds and their risk levels. The firm has already secured a $145 million settlement with Deutsche Bank Securities Inc. and a $20.5 million settlement with Citigroup Inc.

The firm is awaiting a ruling by an Illinois state court judge on its petition to restore a $10.1 billion 2003 verdict against Philip Morris Inc. that the Illinois Supreme Court reversed in 2005. The plaintiffs are Illinois smokers who allege the company used false and deceptive advertising to sell its “light” cigarettes.