In 1992, anti-abortion groups thought they had a winning case in defense of a restrictive Pennsylvania state law. There appeared to be five votes on the U.S. Supreme Court to overrule the landmark decision Roe v. Wade, but that did not happen. As Alabama and Missouri lawmakers adopt strict anti-abortion laws, and predict successful outcomes at the high court, history provides some lessons: Never bet on what occurs behind the high court’s closed conference doors.

After oral arguments in Planned Parenthood of S.E. Pennsylvania v. Casey, Justices Harry Blackmun and John Paul Stevens believed the 1973 ruling in Roe was doomed.