"It wasn't a total surprise; Smith had, for many weeks, said he was thinking about adding the amendment. Incongruously, he was a longtime supporter of the Equal Rights Amendment and the National Women's Party. Women's groups started pressuring him, saying: Listen, if this bill passes, black women will enjoy more protection in the workplace—by virtue of their race—than white women. So Smith was worried that white women might have less coverage, but he also did have a real, genuine support for women's rights and believed that if this bill was going to pass, women should be a part of it."
Mark Joseph Stern interviews attorney and author Gillian Thomas in Slate about sex discrimination and the Civil Rights Act of 1964.