Opinion of the Court
42 U. S. C. §1983, was not prominent until the mid-20th century. See Monroe v. Pape, 365 U. S. 167, 180 (1961); see also R. Fallon, J. Manning, D. Meltzer, & D. Shapiro, Hart and Wechsler’s The Federal Courts and the Federal System 994 (7th ed. 2015). To this day, many federal constitutional rights are as a practical matter asserted typically as defenses to state-law claims, not in federal pre-enforcement cases like this one. See, e.g., Snyder v. Phelps, 562 U. S. 443 (2011) (First Amendment used as a defense to a state tort suit).
Finally, Justice Sotomayor contends that S. B. 8 “chills” the exercise of federal constitutional rights. If nothing else, she says, this fact warrants allowing further relief in this case. Post, at 1–2, 7–8. Here again, however, it turns out that the Court has already and often confronted—and rejected—this very line of thinking. As our cases explain, the “chilling effect” associated with a potentially unconstitutional law being “ ‘on the books’ ” is insufficient to “justify federal intervention” in a pre-enforcement suit. Younger v. Harris, 401 U. S. 37, 42, 50–51 (1971). Instead, this Court has always required proof of a more concrete injury and compliance with traditional rules of equitable practice. See Muskrat, 219 U. S., at 361; Ex parte Young, 209 U. S., at 159–160. The Court has consistently applied these requirements whether the challenged law in question is said to chill the free exercise of religion, the freedom of speech, the right to bear arms, or any other right. The petitioners are not entitled to a special exemption.
Maybe so, Justice Sotomayor replies, but what if other States pass legislation similar to S. B. 8? Doesn’t that possibility justify throwing aside our traditional rules? Post, at 10. It does not. If other States pass similar legislation, pre-enforcement challenges like the one the Court approves today may be available in federal court to test the constitutionality of those laws. Again, too, further pre-enforcement challenges may be permissible in state court and federal
