Central to the Supreme Court’s campaign finance decisions in the John Roberts era is that the government’s only legitimate interest in this area is preventing direct, quid pro quo corruption — a donor demanding that a specific law be passed, or killed, in exchange for cash — or the appearance of direct corruption.

In the McCutcheon decision announced on Wednesday, the court struck down a limit on how much cash an individual could give to all federal candidates during an election cycle. The five conservative justices allowed that the rich showering friendly candidates with unlimited amounts of money might drown out the voices of the majority and distort our fragile democracy, but not blatantly enough to justify the spending limit.

In the majority opinion, Chief Justice Roberts wrote that “government regulation may not target the general gratitude a candidate may feel toward those who support him or his allies, or the political access such support may afford.”

The conservative majority passed on an opportunity to strike down a limit on how much a donor can give to an individual candidate — perhaps because in Citizens United, they’d accepted the proposition that unlimited donations to “independent” third party groups didn’t lend the appearance of corruption — but Justice Clarence Thomas, in his concurring opinion, wrote that “limiting the amount of money a person may give to a candidate does impose a direct restraint on his political communication,” and moved to strike that provision down as well.

The court’s four-member minority issued a blistering dissent, written by Justice Stephen Breyer. He charged that the majority’s “conclusion rests upon its own, not a record-based, view of the facts.”

Its legal analysis is faulty: It misconstrues the nature of the competing constitutional interests at stake. It understates the importance of protecting the political integrity of our governmental institutions. It creates a loophole that will allow a single individual to contribute millions of dollars to a political party or to a candidate’s campaign.

Taken together with Citizens United, Breyer writes that McCutcheon “eviscerates our Nation’s campaign finance laws, leaving a remnant incapable of dealing with the grave problems of democratic legitimacy that those laws were intended to resolve.”

He goes on to dissect the claims on which the court’s ruling rest. He first takes issue with the idea that the government only has an interest in preventing a direct exchange of cash for votes.

In the plurality’s view, a federal statute could not prevent an individual from writing a million dollar check to a political party (by donating to its various committees), because the rationale for any limit would “dangerously broade[n] the circumscribed definition of quid pro quo corruption articulated in our prior cases.” This critically important definition of “corruption” is inconsistent with the Court’s prior case … and it misunderstands the constitutional importance of the interests at stake. In fact, constitutional interests—indeed, First Amendment interests—lie on both sides of the legal equation. In reality, as the history of campaign finance reform shows and as our earlier cases on the subject have recognized, the anticorruption interest that drives Congress to regulate campaign contributions is a far broader, more important interest than the plurality acknowledges. It is an interest in maintaining the integrity of our public governmental institutions. And it is an interest rooted in the Constitution and in the First Amendment itself. Consider at least one reason why the First Amendment protects political speech. Speech does not exist in a vacuum. Rather, political communication seeks to secure government action. A politically oriented “marketplace of ideas” seeks to form a public opinion that can and will influence elected representatives…. The First Amendment advances not only the individual’s right to engage in political speech, but also the public’s interest in preserving a democratic order in which collective speech matters. What has this to do with corruption? It has everything to do with corruption. Corruption breaks the constitution­ally necessary “chain of communication” between the people and their representatives. It derails the essential speech-to-government-action tie. Where enough money calls the tune, the general public will not be heard. Insofar as corruption cuts the link between political thought and political action, a free marketplace of political ideas loses its point. That is one reason why the Court has stressed the constitutional importance of Congress’ concern that a few large donations not drown out the voices of the many…. The “appearance of corruption” can make matters worse. It can lead the public to believe that its efforts to communicate with its representatives or to help sway public opinion have little purpose. And a cynical public can lose interest in political participation altogether.

Breyer then wonders how the conservatives could square McCutcheon’s narrow definition of “corruption” with its conclusion, in the 2003 case McConnell v. FEC, that money — and the access it purchases — has a pernicious influence on the political process.

The Court in McConnell upheld these new contribution restrictions under the First Amendment for the very reason the plurality today discounts or ignores. Namely, the Court found they thwarted a significant risk of corruption—understood not as quid pro quo bribery, but as privileged access to and pernicious influence upon elected representatives. In reaching its conclusion in McConnell, the Court relied upon a vast record compiled in the District Court. That record consisted of over 100,000 pages of material and included testimony from more than 200 witnesses. What it showed, in detail, was the web of relationships and understandings among parties, candidates, and large donors that underlies privileged access and influence. The District Judges in McConnell made clear that the record did “not contain any evidence of bribery or vote buying in exchange for donations of nonfederal money.” Indeed, no one had identified a “single discrete instance of quid pro quo corruption” due to soft money. But what the record did demonstrate was that enormous soft money contributions, ranging between $1 million and $5 million among the largest donors, enabled wealthy contributors to gain disproportionate “access to federal lawmakers” and the ability to “influenc[e] legislation.”

“We specifically rejected efforts to define ‘corruption’ in ways similar to those the plurality today accepts,” writes Breyer.

He then takes on the conservatives’ second rationale: that the problem the aggregate limit was supposed to address — huge donors funneling money indirectly to a candidate in order to get around the limit on contributions to a single campaign — isn’t an issue today.

The plurality is wrong…. In the absence of limits on aggregate political contributions, donors can and likely will find ways to channel millions of dollars to parties and to individual candidates, producing precisely the kind of “corruption” or “appearance of corruption” that previously led the Court to hold aggregate limits constitutional. Those opportunities for circumvention will also produce the type of corruption that concerns the plurality today. The methods for using today’s opinion to evade the law’s individual contribution limits are complex, but they are well known, or will become well known, to party fundraisers.

He offers three concrete examples of how a wealthy donor might be able to get millions of dollars to a single candidate without running afoul of the law under McCutcheon.

But perhaps the dissent’s most withering criticism of the ruling is that, as in Citizens United, it was decided according to the majority’s beliefs, rather than the factual record.