The U.S. Supreme Court on Wednesday ruled that a North Carolina state dental board does not have the authority to regulate teeth-whitening services, accepting the federal government's claim that the system is anticompetitive because dentists sit on the panel.

The court, on a 6-3 vote, ruled for the U.S. Federal Trade Commission, which had decided that the North Carolina State Board of Dental Examiners could be subject to antitrust claims.

The justices, in an opinion by Justice Anthony Kennedy, agreed with the government's claim that although state entities are usually exempt from federal antitrust laws, the exemption did not apply because the board was not actively supervised by the state and because it was made up of self-interested private businesses.

Kennedy wrote that the exemption "does not authorize the states to abandon markets to the unsupervised control of active market participants."

FTC Chairwoman Edith Ramirez said she was pleased with the ruling and noted that the board had barred non-dentists from offering cheaper teeth-whitening services.

"The court's decision makes clear that state agencies (the dental board) constituted in this manner are subject to the federal antitrust laws unless the state actively supervises their decisions," Ramirez said in a statement.

The FTC filed an administrative complaint against the board in 2010, claiming it violated a section of the Federal Trade Commission Act that prohibits unfair methods of competition and deceptive acts and practices in commerce.

The FTC has said in court filings that the board is more akin to a trade association and was seeking to exclude non-dentists from the teeth-whitening market in order to freeze out potential competitors.

Prior to the board's action, teeth-whitening services that were cheaper than those provided by dentists were available at malls and salons. Under North Carolina law, it has not been specified if teeth-whitening is a service that is exclusively under the purview of dentists.

In May 2013, the Richmond-based 4th U.S. Circuit Court of Appeals ruled in favor of the FTC.

The case is North Carolina Board of Dental Examiners v. FTC, U.S. Supreme Court, No. 13-534.