The justices declined, without comment, to consider the constitutionality of a voluntary program passed by the Legislature and that took effect in 2004.

The program provides campaign money for state Supreme Court and Court of Appeals candidates if they agree to fundraising restrictions leading up to the general election. The decision came on the eve of an election in which all but two of the 13 candidates for those seats Tuesday participated in the program.

The decision leaves a federal lower court ruling in effect that upheld the law, which has been a model for other states, including New Mexico.

"This gives supporters of judicial public financing and public financing in general confidence and assurance that the long line of decisions (supporting) public financing ... are still the law of the land," said Paul Ryan, an attorney with the Washington-based Campaign Legal Center, whose group earlier filed a friend-of-the-court brief in support of the law.

Former Supreme Court candidate Rusty Duke and the North Carolina Right to Life Committee sued over the law in 2005, arguing it restricted free speech rights in cases where outside groups or nonparticipating candidates exceeded spending thresholds.

The qualifying candidates receive matching "rescue funds" to counter such injections of money.

The state's requirements that privately funded candidates and independent expenditure groups must file additional paperwork when they spend money to determine if rescue funds are triggered also "impose a substantial unconstitutional burden on the political speech" of these entities, according to the plaintiff's petition.

The Richmond, Va.-based 4th U.S. Circuit Court of Appeals sided with the state in May. Attorneys for Duke and the group asked the high court unsuccessfully to consider the case in part because interest in public financing has expanded nationwide.