The Supreme Court heard arguments in McComish v. Bennett today, which the SCOTUSBlog describes as a case determining "whether the First Amendment prohibits a state from giving additional money to a candidate who accepts state funding for her campaign whenever: (a) an independent group spends more than a certain amount campaigning against the candidate; or (b) the candidate's opponent refuses public funding and spends more than a certain amount on the campaign."
The petitioner in this case represents the Arizona Free Enterprise Club's (AZFEC) Freedom Club PAC, a free-market non-profit in Arizona that is challenging that state's "matching funds" law. According to the law, if a group like AZFEC donates to a candidate who has declined public funding and that candidate's total funds raised exceeds a set limit, the opponents of that candidate can receive the difference from public funds.
Essentially, the petitioners are arguing that the law discourages independent groups from donating to candidates, since any donations over the total limit will simply be given to their preferred candidates' opponents.
What's interesting about the case is the list of people and groups who filed amicus briefs on behalf of the Arizona law's defenders. According to SCOTUSBlog, that list includes left-wing groups like the ACLU, the Service Employees International Union (SEIU), the Citizens for Responsibility and Ethics in Washington (CREW), and the Sierra Club. Additionally, the group of "self-financed" candidates who also filed amicus briefs in defense of the "matching funds law" include former congressmen Bill Foster, Alan Grayson, Walt Minnick, and Steve Kagen, former Maine governor Angus King, former Senate candidate Ned Lamont, and current congressmen Jared Polis and John Yarmuth--liberal Democrats all.