Opinion of the Court
even a sizeable sphere has borders.[1]
B
Petitioners contend that ICWA exceeds Congress’s power. Their principal theory, and the one accepted by both Justice Alito and the dissenters in the Fifth Circuit, is that ICWA treads on the States’ authority over family law. Domestic relations have traditionally been governed by state law; thus, federal power over Indians stops where state power over the family begins. Or so the argument goes.
It is true that Congress lacks a general power over domestic relations, In re Burrus, 136 U. S. 586, 593–594 (1890), and, as a result, responsibility for regulating marriage and child custody remains primarily with the States, Sosna v. Iowa, 419 U. S. 393, 404 (1975). See also Moore v. Sims, 442 U. S. 415, 435 (1979). But the Constitution does not erect a firewall around family law. On the contrary, when Congress validly legislates pursuant to its Article I powers, we “ha[ve] not hesitated” to find conflicting state family law preempted, “[n]otwithstanding the limited application of federal law in the field of domestic relations generally.” Ridgway v. Ridgway, 454 U. S. 46, 54 (1981) (federal law providing life insurance preempted state family-property law); see also Hillman v. Maretta, 569 U. S. 483, 491 (2013) (“state laws ‘governing the economic aspects of domestic relations … must give way to clearly conflicting federal enactments’ ” (alteration in original)). In fact, we have specifically recognized Congress’s power to displace
- ↑ Justice Alito’s dissent criticizes the Court for “violating one of the most basic laws of logic” with our conclusion that “Congress’s power over Indian affairs is ‘plenary’ but not ‘absolute.’ ” Post, at 3–4. Yet the dissent goes on to make that very same observation. Post, at 4 (“[E]ven so-called plenary powers cannot override foundational constitutional constraints”).
