Roberts, C.J., concurring in judgment
rule—from our jurisprudence.
The majority lists a number of cases that have stressed the importance of the viability rule to our abortion precedents. See ante, at 73–74. I agree that—whether it was originally holding or dictum—the viability line is clearly part of our “past precedent,” and the Court has applied it as such in several cases since Roe. Ante, at 73. My point is that Roe adopted two distinct rules of constitutional law: one, that a woman has the right to choose to terminate a pregnancy; two, that such right may be overridden by the State’s legitimate interests when the fetus is viable outside the womb. The latter is obviously distinct from the former. I would abandon that timing rule, but see no need in this case to consider the basic right.
The Court contends that it is impossible to address Roe’s conclusion that the Constitution protects the woman’s right to abortion, without also addressing Roe’s rule that the State’s interests are not constitutionally adequate to justify a ban on abortion until viability. See ibid. But we have partially overruled precedents before, see, e.g., United States v. Miller, 471 U. S. 130, 142–144 (1985); Daniels v. Williams, 474 U. S. 327, 328–331 (1986); Batson v. Kentucky, 476 U. S. 79, 90–93 (1986), and certainly have never held that a distinct holding defining the contours of a constitutional right must be treated as part and parcel of the right itself.
Overruling the subsidiary rule is sufficient to resolve this case in Mississippi’s favor. The law at issue allows abortions up through fifteen weeks, providing an adequate opportunity to exercise the right Roe protects. By the time a pregnant woman has reached that point, her pregnancy is well into the second trimester. Pregnancy tests are now inexpensive and accurate, and a woman ordinarily discovers she is pregnant by six weeks of gestation. See A. Branum & K. Ahrens, Trends in Timing of Pregnancy Awareness Among US Women, 21 Maternal & Child Health J. 715, 722
