In a rare legal broadside by a politician against a major news organization, Lt. Gov. Justin E. Fairfax of Virginia sued CBS on Thursday for defamation, saying the network’s news division smeared him by airing interviews with two women who accused the lawmaker of sexual assault.

Mr. Fairfax, who remained in his job despite an outcry after the assault accusations, asked CBS to pay him $400 million in damages. He said the network ignored evidence that the women’s accounts were untruthful, and he argues that the reports damaged his career and reputation.

CBS News, in a statement, said: “We stand by our reporting and we will vigorously defend this lawsuit.”

The suit, filed in Federal District Court in Alexandria, Va., concerns a pair of interviews that aired in April on “CBS This Morning,” conducted by the anchor Gayle King. One woman, Meredith Watson, accused Mr. Fairfax of raping her in 2000 in a fraternity house at Duke University, where they were students. Another woman, Vanessa C. Tyson, a professor of political science, described being sexually assaulted by Mr. Fairfax after they met at the 2004 Democratic National Convention in Boston.