On Wednesday, the Guardian broke an explosive story about how Wisconsin's Republican Gov. Scott Walker sidestepped campaign finance laws to raise huge donations from corporations and wealthy individuals for his 2012 recall election. Of course, it's not at all surprising to see a politician go after big money contributors. The way he did so, however, undermines key assumptions in the U.S. Supreme Court's infamous Citizens United case, and is certainly the single strongest piece of evidence yet that the logic of that ruling is unsustainable and will have to be revisited by the court.

The documents published by the Guardian indicate that Walker's campaign committee worked closely with a group called Wisconsin Club for Growth, which was operated by one of his campaign consultants. Walker apparently held a series of meetings with wealthy businessmen just before his recall election, and emails show his fundraising team instructing him to ask for money – not for his campaign, but for the group. In March 2012, for example, Walker's finance director sent him an email to prepare him for a meeting with the business mogul Carl Icahn, and noted that "[t]his meeting is for [Wisconsin Club for Growth] Funds." And after a 2011 meeting with the owner of a home improvement chain, Walker emailed his campaign team to tell them "I got $1 [million] from John Menard today." Menard's corporation later sent a million dollar check to the Wisconsin Club for Growth.

The appeal of a pass-through entity like the Wisconsin Club for Growth is obvious. Whereas Walker's campaign committee was subject to contribution limits and disclosure rules, the group could raise unlimited contributions and keep its donors secret, even as Walker's control of the entity still guaranteed that its ads would contain – as another email put it – all the "correct messaging."

You don't need to be an election lawyer to see this reduces campaign finance rules to a farce. In Citizens United, the Supreme Court invalidated political spending limits for corporations like the Wisconsin Club for Growth because it assumed that such spending would be independent of candidates' campaigns and fully transparent, and so pose little corruption risk. The court held that limits on direct contributions to candidates and disclosure were enough to protect the integrity of our political system. But such rules are pointless if a candidate can get around them as easily as Walker did.

These revelations are a stark example of what most political practitioners already know: Candidates and supportive groups like the Wisconsin Club for Growth often coordinate their activities with one another to get around campaign finance rules. In 2014, the Brennan Center released a report documenting many instances of such coordination and showing how hard it is to write and enforce laws to prevent it. The problem has likely only gotten worse as candidates and groups have become more sophisticated and realized the potential benefits and low risk of coordinating their spending.

Far too often, powerful interests align to shield such conduct from public scrutiny. The Guardian revelations came to light only because of a years-long investigation that the Wisconsin Supreme Court shut down earlier this year in a breathtaking opinion that ignored 40 years of guiding precedent. As the Guardian article points out, the Wisconsin Club for Growth spent millions to support the election of Justice David Prosser, one of the Wisconsin judges who voted to end the investigation. The Wisconsin court's ruling is on appeal to the U.S. Supreme Court, and it is possible that this particular situation is so outrageous that the high court will feel compelled to intervene. (The Brennan Center filed an amicus brief in this case.)