1972 Miers was a law clerk for the Chief Judge of the U.S. District Court for the Northern District of Texas, Joe E. Estes. She was admitted to the State Bar of Texas in 1970 and admitted to the DC bar in 1997. In the late 1990s, while Miers was on the advisory board for Southern Methodist University's law school, she helped create and fund a Women's Studies lecture series named after pioneering Texas lawyer Louise B. Raggio, who was a mentor to Miers. Raggio, who died in 2011, knew Miers for nearly 40 years, since Miers was a student at Southern Methodist University. Miers was one class behind Raggio's son at SMU, and Raggio became a mentor for Miers; years later she served as a close advisor to Miers during the Texas Bar race. "I was interested in having a woman president," Raggio says. "She was an electable woman, a woman with a big firm behind her. Women's groups supported her because they wanted to show that a woman would be a competent president.". From 1972 until 2001 Miers worked for the Dallas law firm of Locke, Liddell & Sapp (and predecessor firms before mergers). She was the first female lawyer hired by the firm and later became its president. When the merger that created Locke, Liddell & Sapp took place in 1999, she became the co-managing partner of a legal business with more than 400 lawyers. In 2000 the firm settled a lawsuit for $22 million that accused the firm of having "aided a client in defrauding investors". According to the Class Action Reporter, Miers "said the firm denies liability in connection with its representation of Erxleben. 'Obviously, we evaluated that this was the right time to settle and to resolve this matter and that it was in the best interest of the firm to do so,' Miers said." As a commercial litigator, she represented clients including Microsoft and the Walt Disney Company. In 1985, Miers became the first female president of the Dallas Bar Association. In 1992, Miers became the first woman to head the State Bar of Texas. From 1989 to 1998, she headed the Board of Editors for the American Bar Association Journal. From 2000 to 2001, Miers chaired the ABA's Commission on Multi-Jurisdictional Practice. In 1989, Miers formally registered with the Republican Party and was elected to a two-year term as an at-large member