In a historic decision, the U.S. Supreme Court rules in Roe v. Wade that women, as part of their constitutional right to privacy, can terminate a pregnancy during its first two trimesters. Only during the last trimester, when the fetus can survive outside the womb, would states be permitted to regulate abortion of a healthy pregnancy.

The controversial ruling, essentially reversing a century of anti-abortion legislation in the United States, was the result of a call by many American women for control over their own reproductive processes. Although defended by the Supreme Court on several occasions, the legalization of abortion became a divisive and intensely emotional public issue. The debate intensified during the 1980s, and both pro-choice and pro-life organizations strengthened their membership and political influence.

Republican presidents Ronald Reagan and George Bush used their executive authority to legislate abortion clinic guidelines that restricted free practice of the procedure. However, in 1986, and again in 1989 and 1992, the Supreme Court narrowly reaffirmed the decision, and in 1993 President Bill Clinton, a Democrat, overturned his predecessors’ anti-abortion legislation within days of taking office. In the 1990s, opponents of abortion rights increasingly turned to violent methods in their campaign to make abortion illegal again.

In 2005, the retirement of Supreme Court justice Sandra Day O’Connor, who though conservative had helped block efforts to overturn Roe v. Wade, led to fears that the historic legislation might be vulnerable to reversal.