The laws help state candidates who eschew private campaign financing in favor of varying state subsidies.
A key high court swing vote, Justice Anthony Kennedy, repeatedly expressed his skepticism during argument about the Arizona campaign finance laws, SCOTUSBLOG.com reported. Kennedy asked, "Do 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?"
A lawyer opposing the laws, William Maurer of Seattle, agreed and responded, "Limiting spending indicates that they wanted less political speech in the state of Arizona, and that's what they've got," SCOTUSBLOG reported.
Kennedy was instrumental in the 5-4 conservative majority last year that struck down restrictions on political contributions by corporations and unions.
In accepting the dispute last November, the high court agreed to hear the issues of two combined cases involving the state's Clean Elections program.
In the first, the question is whether the First Amendment prohibits states from giving additional government subsidies to publicly financed candidates when those subsidies are triggered by independent expenditure groups acting on behalf of privately financed candidates.
In the second, one question is whether Arizona's "matching funds trigger" -- the condition that kicks in public matching funds measured by independent expenditures or by the raising and spending of money by privately financed candidates and their supporters -- also violates the First and 14th Amendments.
Also in the second of the combined cases is the question of whether Arizona law violates those amendments by regulating campaign financing "to equalize resources among competing candidates and interest groups, rather than advancing a compelling state interest in the least restrictive manner."
The high court in June blocked a portion of the Clean Elections program in which the state provided "matching funds" to privately financed candidates, meaning they were unavailable in the last election cycle.
Challengers of the law said it unconstitutionally limits the free speech of privately funded candidates who were forced to cut back spending to avoid letting their opponents receive more public money.
A federal judge agreed with the challengers, but the 9th U.S. Court of Appeals supported the state laws.
The Supreme Court should render a decision before the close of the term in late June or early July.