Opinion of the Court
authority to regulate first trimester abortions for the purpose of protecting a woman’s health? The Court’s only explanation was that mortality rates for abortion at that stage were lower than the mortality rates for childbirth. Id., at 163. But the Court did not explain why mortality rates were the only factor that a State could legitimately consider. Many health and safety regulations aim to avoid adverse health consequences short of death. And the Court did not explain why it departed from the normal rule that courts defer to the judgments of legislatures “in areas fraught with medical and scientific uncertainties.” Marshall v. United States, 414 U. S. 417, 427 (1974).
An even more glaring deficiency was Roe’s failure to justify the critical distinction it drew between pre- and post-viability abortions. Here is the Court’s entire explanation:
“With respect to the State’s important and legitimate interest in potential life, the ‘compelling’ point is at viability. This is so because the fetus then presumably has the capability of meaningful life outside the womb.” 410 U. S., at 163.
As Professor Laurence Tribe has written, “[c]learly, this mistakes ‘a definition for a syllogism.’ ” Tribe 4 (quoting Ely 924). The definition of a “viable” fetus is one that is capable of surviving outside the womb, but why is this the point at which the State’s interest becomes compelling? If, as Roe held, a State’s interest in protecting prenatal life is compelling “after viability,” 410 U. S., at 163, why isn’t that interest “equally compelling before viability”? Webster v. Reproductive Health Services, 492 U. S. 490, 519 (1989) (plurality opinion) (quoting Thornburgh, 476 U. S., at 795 (White, J., dissenting)). Roe did not say, and no explanation is apparent.
This arbitrary line has not found much support among philosophers and ethicists who have attempted to justify a right to abortion. Some have argued that a fetus should not
