In two consolidated cases on Monday, the Supreme Court will hear argument about an Arizona law that levels the playing field in state elections, by a public financing mechanism called triggered matching funds. These funds support, expand and promote political speech, carrying out a central purpose of the First Amendment.

The mechanism has the bipartisan support of business leaders as “a welcome increase in speech, not a limitation of speech.” It has the support of respected former state judges who know that this and similar public financing mechanisms are the best way to eliminate corruption from state judicial elections. It deserves the Supreme Court’s strong endorsement.

Arizona provides a set amount of money in initial public support for a campaign to candidates who opt into its financing system, depending on the type of election. If such a candidate faces a rival who has opted out, the state will match what the opponent raises in private donations, up to triple the initial amount. The amount raised in private donations triggers the matching funds.

Three years ago, the court struck down the “millionaires’ amendment” to the McCain-Feingold federal election law, which leveled the field in federal elections in a different way, by raising limits on contributions for candidates outspent by self-financed opponents. Writing for the majority, Justice Samuel Alito Jr. called it “an unprecedented penalty on any candidate who robustly exercises” free-speech rights. Translation: rich enough to spend his own money on a campaign.