On the first anniversary of the Supreme Court's ruling in Citizens United, which overturned nearly a century of restrictions on campaign spending, a progressive group has asked the Department of Justice to look into "conflicts of interest" two justices may have had when issuing the ruling.

In a petition to be sent to the department this week, Common Cause will argue that Justices Antonin Scalia and Clarence Thomas should have recused themselves from the campaign finance decision because of their involvement with Koch Industries, a corporation run by two conservative activists who many say directly benefited from Citizens United.

“It appears both justices have participated in political strategy sessions, perhaps while the case was pending, with corporate leaders whose political aims were advanced by the decision,” the letter alleges, as quoted at Politico.

The group will urge the department to disqualify Scalia and Thomas from the ruling. If that were to happen, the Supreme Court could vacate the ruling, effectively returning the campaign finance restrictions that existed until 2010. But, as Common Cause itself admits, the odds are against it.

At the center of the group's claims is a document from Koch Industries unearthed last fall by ThinkProgress and the New York Times. In an invitation to a Palm Springs retreat to be held this month, Charles Koch boasted that previous events were attended by Scalia and Thomas.

If Scalia or Thomas attended a Koch event between 2008 and 2010, when the court was dealing with issues affecting Citizens United, “it would certainly raise serious issues of the appearance of impropriety and bias,” the Commons Cause petition states, as quoted in the New York Times.

Since the Citizens United ruling, many critics have focused on the role of the Koch brothers in US politics, arguing that the oil-business billionaires have placed themselves at the nexus of big business and conservative politics.

The Koch brothers are generally believed to be behind Americans for Prosperity, a group that has been accused of distorting facts in campaigning against health care reform and climate change legislation. President Obama last fall referred to the group as an example of how Citizens United has allowed large corporations to use political groups to funnel unlimited amounts of money into campaigns.

“They don’t have to say who, exactly, Americans for Prosperity are," Obama said. "You don’t know if it’s a foreign-controlled corporation [or even] a big oil company.”

Steven Gillers, a legal ethics professor at NYU, told the Times that Common Cause's campaign is "a steep uphill climb ... but not an insurmountable one." He suggested that even if the effort failed, it would still allow for a "public airing" of concerns surrounding the Supreme Court's impartiality.

But Rick Hasen, an election law expert at UC-Irvine, had far less faith in Common Cause's effort.

“I am a big critic of the Citizens United case. I would love to see it reversed,” Hasen told Politico. “But this approach seems both unlikely to yield the desired result of seeing the case overturned and appears to be an unwarranted attack on the ethics of the Justices.”

Hasen noted, “Justice Scalia has refused to recuse himself from cases involving a far closer relationship."

Arn H. Pearson, a Common Cause vice president, made it clear that the group doesn't see its effort as an open-and-shut case.

“We’re treading in new territory here for us,” he told the Times. “But a situation like this raises fundamental questions about public confidence in the Supreme Court.”