In the defining First Amendment cases, a political majority is attempting to entrench itself by censoring speech that it deems to be dangerous. The free speech principle forbids this kind of self-entrenchment. It ensures political liberty, and with respect to ideas, a kind of political equality. With campaign finance regulation, the goal is not to entrench the power or opinions of the majority, but to ensure that economic inequalities are not turned into political ones. In a society that tolerates disparities in wealth, that is not merely a worthy goal; it is essential.
In short, for Sunstein there's nothing repressive about limits on campaign spending, but defenders of unlimited spending will disagree. They have often argued that the object of regulation and limitation is to entrench the power (if not the opinions) of a temporary political majority. What they see, and what Sunstein presumably doesn't, is the emergence of a self-interested political class that wishes to exclude others, and in particular the wealthy, from power or influence. This political class, as you've heard before, consists mainly of Democrats but includes some arrogant Republicans, most notably Senator McCain. This political class, the Democrats presumably more than the Republicans, maintains an adversarial relationship toward the wealthy or certain segments of the upper class. The political class is thus a demagogic bureaucracy that seeks to hold power by stirring up envy of the rich. Such a class has an obvious interest, from this perspective, in controlling the narrative and not allowing anyone to challenge it. While the First Amendment forbids the political class from forbidding absolutely any challenge from the wealthy, that class uses campaign-finance to minimize if not marginalize a legitimate challenge. While advocates of stricter regulations like Sunstein and Justice Stevens are vigilant against the wealthy acquiring too much voice in elections, opponents of all regulations see a tendency to deny the wealthy any voice, or any voice sufficient to overcome the alleged benefits of incumbency.
Sunstein answers that, "to be sure, some campaign finance restrictions could turn out to be measures that protect incumbents. But the best way to combat that risk is through democratic debate, not through judicially imposed constraints on campaign finance laws as such." But the other side will argue that that "democratic debate" itself is compromised if the political class sets terms for it favorable to itself. Here's the sticking point. One group of people will resist any regulation of campaign donations so long as they assume an adversarial relationship between public and private sectors, seeing restrictions on spending as the repression of the latter by the former. While this particular debate has heated up in recent years, it's really an old story. At its heart is a concept of class conflict as old as classical political theory. It sees "wealth" or "property" as a constituent element of the political order that must be balanced with but not overwhelmed by the interests of the many. States throughout history have been torn by conflicting imperatives: to protect what people have and/or to provide what people need. If the political balance tips toward the latter, society's haves feel threatened and demand that their concerns be heard by all. To deny them the ability to use the resources at their disposal to get their message out, from their own perspective, would be like limiting how long the silver-tongued orator can speak so that he can barely get started, or how many people can show up on the streets to protest anything, so that all demonstrations look pathetically small. The Koch brothers could say that limiting what they can spend is like putting them in one of those Orwellian "free speech zones" far from the people you want to confront. But I doubt whether the analogy occurs to them, since they seem concerned primarily with the rights of wealth rather than with the rights of people. Wealth, they mean, has a right to our attention that the political class can't deny, since it has a right to protection from the greed of the state and the masses. That's what the debate is about, at bottom -- not simply the right to say that your government is wrong. What may really be at stake is anyone's right to say that wealth, or its self-appointed representatives, are wrong.