CREDIT: IStockThe eight Supreme Court justices will return from their summer vacations Monday to consider a backlog of petitions asking the Court to review a pile of cases. One of these cases, Chisholm v. Two Unnamed Petitioners, asks whether conservative justices on the Wisconsin Supreme Court violated the Constitution by failing to recuse from a criminal investigation targeting groups that spent millions of dollars to get them elected.The case arises out of a campaign finance investigation into whether Gov. Scott Walker and other legislators illegally “coordinated” their campaigns with outside groups, some of which could accept unlimited, secret donations. Newly leaked documents suggest close ties between these groups and the Wisconsin governor’s campaign. They also suggest similar ties between the groups and a recently retired member of the Wisconsin Supreme Court.Prosecutors allege that two Wisconsin justices who heard the case involving the Walker investigation, now-retired Justice David Prosser and current Justice Michael Gableman, committed the same offense that is at the heart of the Walker case by coordinating their own campaigns with the same groups. Nevertheless, Prosser and Gableman refused to sit out the case, and they later voted to shut down the Walker investigation in July 2015.Additionally, the state supreme court required extensive redactions in the court filings and also ordered prosecutors to “permanently destroy all copies of information and other materials obtained through the investigation.” The court later backtracked on its order to destroy the evidence, and The Guardian obtained much of this information and published it last week.Among other things, the leaked documents show that Walker steered donors to give six-figure checks to the Wisconsin Club for Growth, a nonprofit operating under Section 501(c)(4) of the tax code. One of the donors even wrote “Because Scott Walker asked” on the subject line of his check to the group. An email from Walker to GOP strategist Karl Rove noted that RJ Johnson — who The Guardian described as a central figure in both Walker’s campaign and the Wisconsin Club for Growth — “ran the effort” to elect Justice Gableman in 2008. The email also said the club “was the key to retaining Justice Prosser.”In justifying their decision not to recuse from this case, Prosser and Gableman cited a Wisconsin Supreme Court rule on cases involving campaign contributors that was literally written by one of the groups at issue in this case — Wisconsin Manufacturers & Commerce. Under this rule, campaign contributions can never be the sole basis for a judge’s recusal. When the rule was put in place dissenting Justice Ann Walsh Bradley criticized her colleagues for adopting “word-for-word the script of special interests that may want to sway the results of future judicial campaigns.”Prosecutors argue that the U.S. Supreme Court should intervene, citing fairly recent precedents limiting judges’ ability to sit on cases involving their campaign benefactors. In 2009, the U.S. Supreme Court ruled that a West Virginia justice violated the Constitution by hearing a case involving a coal company whose CEO spent $3 million to get him elected. Even if the justice was not actually biased, the U.S. Supreme Court ruled in Caperton v. Massey Coal, the “risk of actual bias” violated the other party’s Due Process rights.The conflict of interest in this case is similar to the one in Caperton, as parties to both cases spent millions to elect the judges. Wisconsin Justices David Prosser and Michael Gableman benefited from around $2 million worth of outside spending in each of their last elections, while Justice Gableman’s campaign spent just over $400,000, and like the West Virginia justice, the two justices narrowly won their elections after the cash poured in.The U.S. Supreme Court bears a particular burden when state supreme courts engage in questionable practices, as it is the only Court that can review a state supreme court’s decision. The justices will soon decide whether the Wisconsin Supreme Court has the final word in this case.Are judges for sale? The Supreme Court could decide in pending corruption case. was originally published in ThinkProgress on Medium, where people are continuing the conversation by highlighting and responding to this story. Read the responses to this story on Medium.