Outside groups spending money in this year's congressional elections have further discredited the already moribund rationale that the U.S. Supreme Court used to justify its landmark 2010 decision to permit unfettered spending by corporations and unions.

The court's 5-4 decision in Citizens United v. Federal Election Commission was predicated on an assumption that outside organizations that spend money to influence elections are "independent" actors. The court ruled that independent expenditures -- in contrast to direct contributions to candidates -- do not pose a significant risk of fomenting corruption and, therefore, should not be regulated. This led to the rise of the "independent" super PAC.

By the end of the 2012 election cycle, the court's expectation of independence was proven fatally flawed.

Operatives for President Barack Obama and eventual Republican nominee Mitt Romney, for instance, left their candidates' official campaigns to operate super PACs dedicated to those candidates. Both candidates endorsed the groups, and Romney even referred to his as "my super PAC." The two outside groups cumulatively spent nearly $210 million, fueled by contributions of at least $1 million each from 65 donors. Those donors were limited to giving $5,000 to the candidates' official committees.

In 2012, 112 of the unregulated outside spending groups that arose in the wake of Citizens United devoted all or nearly all of their resources to aiding a single candidate, including 62 that were dedicated to helping a single congressional candidate. An individual group's choice to spend on behalf of a single candidate does not prove that the group was somehow connected to the candidate. But the aggregate numbers are telling. How many truly "independent" organizations would just happen to focus on one and only one congressional contest out of 468 choices?

If there was a factor that made dedicated super PACs in 2012 slightly less egregious, it was that many were funded and operated by friends and family -- one was even dubbed "Mama PAC" in the press -- and backed candidates with little chance of winning. Thus, even if most of the single-candidate groups in 2012 were clearly not independent, many were not that consequential, either.

But this year, the pros are getting in on the practice for congressional elections. "Anybody giving advice to campaigns that did not recommend super PACs as part of the strategy mix would be committing political malpractice," former Michigan Republican Party Chairman Saul Anuzis told The Washington Post in June.

A report published today by Public Citizen identifies 57 unregulated outside groups that have spent all of their money on behalf of a single congressional candidate. Many of these groups are operated by the candidates' former finance chairs or others with connections to the candidate and, thus, cannot plausibly be considered independent.

This phenomenon of unregulated outside groups acting like unofficial campaign committees for candidates is the metaphorical equivalent of swinging a wrecking ball at the foundation of the campaign finance system. These groups effectively enable donors to ignore contribution limits.

Observers began portraying Citizens United as eviscerating the campaign finance system almost the moment that the decision was handed down and, in retrospect, rightly so. But it's important to note that the court did not. In the Citizens United decision, the court left limits on contributions to candidates intact and endorsed the thrust of its precedent of permitting restrictions on campaign finance activities that pose a risk of causing corruption.

"If elected officials succumb to improper influences from independent expenditures; if they surrender their best judgment; and if they put expediency before principle, then surely there is cause for concern," the court wrote in Citizens United. "We must give weight to attempts by Congress to seek to dispel either the appearance or the reality of these influences."

The court claimed it struck down rules only on outside expenditures because of their supposed independent nature. That assumption, to borrow a phrase from the era that gave rise to our campaign finance system, is no longer operative.