Opinion of the Court
substantial obstacle “in a large fraction of cases in which [it] is relevant,” 505 U. S., at 895, but there is obviously no clear line between a fraction that is “large” and one that is not. Nor is it clear what the Court meant by “cases in which” a regulation is “relevant.” These ambiguities have caused confusion and disagreement. Compare Whole Woman’s Health v. Hellerstedt, 579 U. S. 582, 627–628 (2016), with id., at 666–667, and n. 11 (Alito, J., dissenting).
2
The difficulty of applying Casey’s new rules surfaced in that very case. The controlling opinion found that Pennsylvania’s 24-hour waiting period requirement and its informed-consent provision did not impose “undue burden[s],” Casey, 505 U. S., at 881–887, but Justice Stevens, applying the same test, reached the opposite result, id., at 920–922 (opinion concurring in part and dissenting in part). That did not bode well, and then-Chief Justice Rehnquist aptly observed that “the undue burden standard presents nothing more workable than the trimester framework.” Id., at 964–966 (dissenting opinion).
The ambiguity of the “undue burden” test also produced disagreement in later cases. In Whole Woman’s Health, the Court adopted the cost-benefit interpretation of the test, stating that “[t]he rule announced in Casey … requires that courts consider the burdens a law imposes on abortion access together with the benefits those laws confer.” 579 U. S., at 607 (emphasis added). But five years later, a majority of the Justices rejected that interpretation. See June Medical, 591 U. S. ___. Four Justices reaffirmed Whole Woman’s Health’s instruction to “weigh” a law’s “benefits” against “the burdens it imposes on abortion access.” 591 U. S., at ___ (plurality opinion) (slip op., at 2) (internal quotation marks omitted). But The Chief Justice—who cast
