Walmart faces a potential class-action lawsuit in New York state for allegations of pregnancy discrimination. Two former Walmart associates claim they were fired for missing work due to pregnancy-related medical issues. Walmart denies the claims. CBS News legal anaylst Rikki Klieman joins "CBS This Morning" to discuss the difficulty in proving pregnancy discrimination. Walmart isn't alone, as other large companies facing legal action include Merck, AT&T, Whole Foods and Novartis.