WASHINGTON — A federal appeals court says the Supreme Court can keep protesters off its marble plaza without violating their constitutional right to free speech.

The US Court of Appeals for the District of Columbia Circuit ruled Friday that First Amendment rights stop at the sidewalk in front of the majestic courthouse and do not extend to the plaza.

The decision reversed a lower court ruling that declared unconstitutional a law prohibiting protests on the plaza.

Since 1983, the Supreme Court had interpreted the law to allow protests and other displays only on the public sidewalk surrounding the building. But that ruling did not directly consider demonstrations on the large marble plaza between the sidewalk and the court’s main entrance.