Justice Breyer, with whom Justice Ginsburg joins, concurring.

[T]he principal dissent oversimplifies the problem faced in the campaign finance context. It takes a difficult constitutional problem and turns it into a lopsided dispute between political expression and government censorship. Under the cover of this fiction and its accompanying formula, the dissent would make the Court absolute arbiter of a difficult question best left, in the main, to the political branches.

        If the dissent believes that the Court diminishes the importance of the First Amendment interests before us, it is wrong. The Court’s opinion does not question the constitutional importance of political speech or that its protection lies at the heart of the First Amendment. ...this is a case where constitutionally protected interests lie on both sides of the legal equation...

[A] decision to contribute money to a campaign is a matter of First Amendment concern–not because money is speech (it is not); but because it enables speech. Through contributions the contributor associates himself with the candidate’s cause, helps the candidate communicate a political message with which the contributor agrees, and helps the candidate win by attracting the votes of similarly minded voters... Both political association and political communication are at stake.

    On the other hand, restrictions upon the amount any one individual can contribute to a particular candidate seek to protect the integrity of the electoral process–the means through which a free society democratically translates political speech into concrete governmental action. [B]y limiting the size of the largest contributions, such restrictions aim to democratize the influence that money itself may bring to bear upon the electoral process. ...In doing so, they seek to build public confidence in that process and broaden the base of a candidate’s meaningful financial support, encouraging the public participation and open discussion that the First Amendment itself presupposes. ...

In service of these objectives, the statute imposes restrictions of degree. It does not deny the contributor the opportunity to associate with the candidate through a contribution, though it limits a contribution’s size. Nor does it prevent the contributor from using money (alone or with others) to pay for the expression of the same views in other ways. Instead, it permits all supporters to contribute the same amount of money, in an attempt to make the process fairer and more democratic.

Under these circumstances, a presumption against constitutionality is out of place. ...

In such circumstances–where a law significantly implicates competing constitutionally protected interests in complex ways–the Court has closely scrutinized the statute’s impact on those interests, but refrained from employing a simple test that effectively presumes unconstitutionality. Rather, it has balanced interests. And in practice that has meant asking whether the statute burdens any one such interest in a manner out of proportion to the statute’s salutary effects upon the others (perhaps, but not necessarily, because of the existence of a clearly superior, less restrictive alternative). Where a legislature has significantly greater institutional expertise, as, for example, in the field of election regulation, the Court in practice defers to empirical legislative judgments–at least where that deference does not risk such constitutional evils as, say, permitting incumbents to insulate themselves from effective electoral challenge. This approach is that taken in fact by Buckley for contributions, and is found generally where competing constitutional interests are implicated, such as privacy, ...

I agree that the legislature understands the problem–the threat to electoral integrity, the need for democratization–better than do we. We should defer to its political judgment that unlimited spending threatens the integrity of the electoral process. But we should not defer in respect to whether its solution, by imposing too low a contribution limit, significantly increases the reputation-related or media-related advantages of incumbency and thereby insulates legislators from effective electoral challenge. ...

The approach I have outlined here is consistent with the approach this Court has taken in many complex First Amendment cases. ...The Buckley decision, as well, might be interpreted as embodying sufficient flexibility for the problem at hand. After all, Buckley’s holding seems to leave the political branches broad authority to enact laws regulating contributions that take the form of “soft money.” It held public financing laws constitutional, ...It says nothing one way or the other about such important proposed reforms as reduced-price media time. ...