(RNS) On Wednesday (March 2), the most important abortion case since 1992’s Planned Parenthood v. Casey will be argued before the U.S. Supreme Court. Casey shifted away from Roe v. Wade’s focus on privacy and instead asked whether abortion restrictions were an “undue burden” on women.The court, however, has not been clear about what “undue burden” means.In 2007’s Gonzales v. Carhart, the last significant abortion case, swing voter Justice Anthony Kennedy joined the four conservatives in ruling that laws against partial-birth abortion were not an undue burden. Legal commentators, like CNN’s Jeffrey Toobin, have worried that Kennedy may have signaled...