The opportunity to make such a sweeping declaration came via two cases which both presented constitutional challenges to state criminal abortion laws. One case came from Texas and the other from Georgia. The Texas case, Roe v. Wade involved a pregnant, single woman, "Roe", who was suing the Dallas County district attorney, Henry Wade, to prevent him from enforcing Texas' abortion prohibition. Since her life was not threatened by her pregnancy, she had no legal basis for aborting in Texas (prohibitive abortion laws had existed in Texas with very little change since 1854, but had always included an exception to save the life of the mother). The Georgia case, Doe v. Bolton, involved a married woman who was also denied an abortion for not meeting the necessary state requirements (Georgia law allowed for abortion if the life or health of the mother was threatened, if the baby was seriously deformed, or if the pregnancy was a result of rape). A three-judge District Court ruled that Roe did have basis to sue, and declared Texas abortion law void for being "vague" and "overbroad". The District Court ruling in the Doe case was split. It ruled that there were some unnecessary bureaucratic burdens that might hinder someone from receiving a due abortion, but they still held that the State had a right to restrict abortion according to the princliples already in place. Both decisions were appealed, both decisions ended up before the Supreme Court, and both verdicts were handed down on the same day, January 22, 1973.

Roe ruled (7-2) that though states did have an interest in protecting fetal life, such interest was not "compelling" until the fetus was viable (placing viability at the start of the third trimester). Thus, all state abortion laws that forbade abortion during the first six months of pregnancy were thereby invalidated. Third trimester abortions, on the other hand, were only legal if the pregnancy threatened the life or health of the mother. The Doe verdict, however, defined "health of the mother" in such broad terms, that any prohibitions to 3rd trimester abortions were essentially eliminated. According to Justice Harry Blackmun's majority opinion, a woman's health includes her "physical, emotional, psychological, (and) familial" well-being, and should include considerations about the woman's age. "All these factors may relate to health," Blackmun argued, so as to give "the attending physician the room he needs to make his best medical judgment." In other words, if a woman is upset about her 3rd trimester pregnancy (psychological health), her doctor has the necessary legal basis to abort.

In 1976, abortion again made its way to the Supreme Court, in Planned Parenthood v. Danforth, where all state laws requiring spousal or parental consent were thrown out. Thornburg v. American College of Obstetricians and Gynecologists, a 1986 case that was split 5-4, struck down all manner of abortion restrictions including the requirement to inform women about abortion alternatives, the requirement to educate women about prenatal development, the requirement to inform women of the potential risks of abortion, the requirement to keep records of abortion, and the requirement that 3rd trimester abortions be performed in such a way as to spare the life of the viable child. All these were argued to be violations of a woman's right to privacy. In 1989, however, in Webster v. Reproductive Health Services, Roe was dealt a serious blow. The court, in a 5-4 opinion, let stand a Missouri statute stating that human life begins at conception, and declared that the state does have a "compelling" interest in fetal life throughout pregnancy. The trimester/viability framework of Roe was basically thrown out, but Justice O'Connor, despite arguing for essentially the same thing in prior case law, withheld her endorsement from the portion of the Webster opinion which would have actually overturned Roe. As such, federal abortion laws remained largely unchanged, but the rationale for such laws began to crumble. Many states took this opportunity to put more restrictive state measures in place. In 1990, two cases (Hodgson v. Minnesota and Ohio v. Akron Center for Reproductive Health) ruled that states requiring parental consent before a minor could have an abortion must allow for a judicial bypass.

The last abortion-related case to reach the Supreme Court came in 1992, Planned Parenthood v. Casey. The right to legal abortion was upheld in the Casey decision, but a 24-hour waiting period was put in place, as well as an informed consent requirement, a parental consent provision, and a record keeping mandate. States were also given more discretion as to when viability begins. Casey was decided 5-4, but the opinion of the Court was essentially divided into three factions. Justices Blackmun and Stevens did not endorse the new "burdens" placed on legal abortion, but were willing to concede to gain the support of Justices O'Connor, Kennedy and Souter who believed that Casey was a happy medium between giving states more control while still upholding the basic conclusions of Roe. Justices Rehnquist, White, Scalia and Thomas dissented altogether, believing Roe had no Constitutional basis to begin with and thereby felt no obligation to uphold it. Today, the language of Casey, more than Roe, serves as the dominant precedent in abortion law.

Despite, the legal wranglings which are documented in the cases above, in a practical sense, very little has changed in the way of abortion law since Roe was first decided. Abortion is still legal in all 50 states. The definition of "health" (which justifies late-term abortions) is still broadly defined, and there are no significant barriers in place to keep a woman from aborting. So far, Roe has carried the day.

Since 1973, it has been the single decision of seven, non-elected justices that has defined federal abortion policy (invalidating 200 years of state law), and it was a decision that was explicitly defended on the basis of ignorance. Justice Harry Blackmun stated in the majority opinion of Roe that, "at this point in the development of man's knowledge," we can “not resolve the difficult question of when life begins”. He further states that “if this suggestion of (fetal) personhood is established, the [case in support of legal abortion] collapses, for the fetus' right to life would then be guaranteed specifically by the (14th) Amendment.” While this claim of, "we just don't know when life begins," was demonstrably false in 1973, it is even more nonsensical today. We do know when life begins. We are "at the point in the development of man's knowledge" where we can "resolve [this] difficult question". Nevertheless, the law remains the same, abortion has become entrenched in American life, and the institution which was hoisted upon us without public debate has become a force to be reckoned with. Like slavery before it, abortion is now central to the lives of many Americans, but no matter what the social cost may be, when laws victimize the weak and vulnerable (rather than protecting them), it is time for those laws to change.