8 FEDERAL ELECTION COMM’N v. TED CRUZ FOR SENATE KAGAN, J., dissenting when he has become able to use the power of public office to the donor’s advantage (the quo). The heightened threat of corruption—and, even more, of its appearance—is self-evident (except, it seems, to observers allergic to all campaign finance regulation). In addressing that special danger, Section 304 is anything but a “prophylaxis-upon-prophylaxis,” as the majority labels it. Ante, at 14. The idea behind that fancy-sounding epithet is just that the statute is a needless precaution: The $2,900 contribution ceiling, the majority asserts, already provides generous protection against the corrupting potential of donations, so the loan-repayment provision is unnecessary. See ibid. But that claim ignores that Section 304 targets only a subset of contributions, which raise (as just described) unique corruption risks. When an added protection addresses an added danger, the existence of a basic protection (however ordinarily ample) fails to show the supplement’s pointlessness. Regular seatbelts might suffice to protect drivers on the interstate, but special belts—and roll cages to boot—are essential measures on the racetrack. So too, a $2,900 cap might suffice to prevent corruption from normal campaign contributions—but not from post-election contributions to repay a candidate’s loan, and thus to enrich him personally. When Congress, as here, responds to a heightened threat with a heightened safeguard, the majority has no call to “greet” it “with a measure of skepticism.” Ibid. Nor does the majority have reason to second-guess Congress’s experience-based judgment about the specially corrupting effects of post-election donations to repay candidate loans. The majority’s first attempt to counter that judgment is that “we are only talking about repayment of a loan”: “If the candidate did not have the money to buy a car before he made a loan to his campaign, repayment of the loan would not change that in any way.” Ante, at 19. But that altogether misses the point. However much money the