In Colautti v. Franklin, 439 U.S. 379 (1979), the Court struck down a statute that governed the determination of viability. Id., at 390-397. In the process, the Court made clear that the trimester framework incorporated only one definition of viability-ours-as we forbade States to decide that a certain objective indicator-"be it weeks of gestation or fetal weight or any other single factor"-should govern the definition of viability. Id., at 389. In that same case, the Court also invalidated a regulation requiring a physician to use the abortion technique offering the best chance for fetal survival when performing postviability abortions. See id., at 397-401.