Washington (CNN) -- The Supreme Court's conservative majority appeared to hold the cards Monday in a key campaign finance reform case involving an Arizona election law that would provide matching funds to underfunded candidates. The justices could continue a recent legal trend and strike down another effort at government restrictions on election spending.
The state law offers extra taxpayer-funded support for office seekers who have been outspent by privately funded opponents or by independent political groups. A key sticking point during the one-hour oral arguments was whether this law was designed to "level the playing field" through a public finance system, a legislative goal the court in the past has said is unconstitutional.
"The purpose of this law is to prevent corruption," said Justice Elena Kagan. "That's what the purpose of all public financing systems are."
"I checked the Citizens' Clean Elections Commission website this morning," said Chief Justice John Roberts, referring to the state agency that administers the public financing program, "and it says that this act was passed to, quote, 'level the playing field' when it comes to running for office. Why isn't that clear evidence that (the law is) unconstitutional?"
The high court last June temporarily blocked enforcement of the "clean elections" law during the 2010 elections, ordering state officials not to distribute money under the measure.
A federal appeals court had earlier approved parts of the sweeping campaign reform law. Several mostly conservative groups -- including current and former Republican state legislators -- subsequently filed an appeal with the high court, claiming their free speech rights were being hurt by the law.
Among other things, they contended private fundraising efforts would be hampered because of public election financing.
Arizona lawmakers have argued there is a compelling state interest in equalizing resources among competing candidates and interest groups. They contend the plan to provide matching funds advances that state interest in the least restrictive manner.
The broader free speech issues will now be resolved by the high court.
In arguments, William Maurer, the attorney opposing the law, suggested it interferes with the "voters' decision as to whom to elect to office, and the purpose of doing that ... (is) to raise the voices of those the government thinks (are) speaking too little and muffle the voices of those the government thinks (are) speaking too much."
When Maurer suggested candidates would be curtailed from fundraising because raising over a certain amount would trigger funding for their opponents, Justice Sonia Sotomayor stepped in. "If you spend it at the time you want to, you collect it at the time you want. The law's not telling you not to do (fundraising). You find it an advantage not to do it, correct? Because your opponent won't speak as loud and won't respond, correct?"
Sotomayor and Kagan -- the two newest justices named by President Obama to the bench -- dominated the arguments favoring the law.
"For 40 years," Kagan said, "what public financing systems have been based upon is the idea that when there is a lot of private money floating around the political system, that candidates and then public officeholders get beholden to various people who are giving that money, and (the officeholders) make actions based on how much they receive from those people, and that's the idea of a public financing system is to try to prevent that."
The Obama administration is backing the Arizona law. Bradley Phillips, attorney for the state, said the proposed system would mean "more speech and more electoral competition." That brought some skepticism from some right-leaning members of the bench.
"You think it would be a fair characterization of this law to say that its purpose and its effect are to produce less speech in political campaigns?" asked Anthony Kennedy, who later suggested that would be the impact. He also asked whether "one reason for people to decline participation in the matching funds program is because they do not want to deter independent expenditures."
Other colleagues echoed the sentiment that a high legal bar must be set before political speech can be restricted, suggesting Arizona may be reaching too far and perhaps influencing elections.
"What you just said was that this law aims to allow publicly financed candidates to run on the same footing as privately financed candidates. Isn't that right?" Justice Samuel Alito said to Phillips. "That's leveling the playing field, isn't it?"
Justice Antonin Scalia also attacked one of the stated purposes of the law. "You come in and say, well, it's perfectly OK because its purpose is to make public funding attractive to candidates. The mere fact that it makes it more attractive does not answer the question whether it's constitutional."
The high court last year issued a landmark ruling on campaign finance reform, striking down a sweeping federal law and giving big business, unions and non-profits more power to spend freely in federal elections.
The so-called "Citizens United" decision has the potential of undoing a century of government efforts to regulate the power of corporations to bankroll American politics, by easing long-standing restrictions on "independent spending" by a range of independent groups seeking a voice in the crowded political debate.
The justices three years ago also struck down the so-called "Millionaire's Amendment" in the McCain-Feingold reform legislation. That provision had eased campaign spending limits for opponents of well-heeled congressional candidates who pour $350,000 or more of their money in an election cycle. The court majority said that any effort to level the playing field violates the First Amendment.
The Arizona law was approved by voters in 1998, when big money donations to state lawmakers was perceived by many reform advocates as creating a culture of corruption.
Opponents of the law say the matching funds scheme promoted by Arizona actually forces some candidates to reduce their own spending for fear of triggering increased money for their opponents. That, they argue, reduces the political speech of self-funded candidates.
The cases are McComish v. Bennett (10-239) and Arizona Free Enterprise Club's Freedom Club PAC v. Bennett (10-238). A ruling is expected by late June.