The Supreme Court on Monday unanimously upheld a Nevada ethics law that governs when lawmakers should refrain from voting on official business because they might have a conflict of interest.

The court reversed a Nevada Supreme Court decision that said elected officials have a constitutional right to vote on official business that the state law violated.

The decision came in the case of Michael Carrigan, a Sparks, Nev., council member who voted on a casino project even though his campaign manager served as a project consultant.

Justice Antonin Scalia, writing for the court, said an elected official's vote "is not his own speech but a mechanical function of government — the commitment of his apportioned share of the legislature's power to the passage or defeat of a particular proposal."

Scalia said conflict-of-interest rules similar to Nevada's "have been commonplace for over 200 years."

The Nevada Commission on Ethics found that Carrigan's vote violated a provision of the ethics law that lays out various relationships that should disqualify an official from voting, including the official's relatives and business associates.

The ethics panel said Carrigan should have abstained from voting because his friend and campaign manager, Carlos Vasquez, also worked as a consultant for the Red Hawk Land Co., which was backing the Lazy 8 casino project.

A federal appeals court has sided with the former Massey Energy in a dispute over the company's investigation of last year's deadly Upper Big Branch mine explosion.

The U.S. Court of Appeals for the District of Columbia ruled Friday that Massey is entitled to appeal restrictions placed on its investigation by federal investigators.

The federal Mine Safety and Health Review Commission had rebuffed Virginia-based Massey's request to appeal the restrictions last year.

Massey wanted the commission to set aside restrictions barring it from taking photos and collecting dust samples from the southern West Virginia mine, among other things.

The appellate court set aside the commission's decision rejecting Massey's appeal.

New Massey owner Alpha Natural Resources declined comment. The federal Mine Safety and Health Administration had no immediate comment.