Ku Klux Klan members who want to adopt a highway in north Georgia have taken their constitutional rights case to the state’s top court.

The Georgia Supreme Court heard arguments Monday about whether the International Keystone Knights of the Ku Klux Klan should be permitted to pick up trash as part of the state’s Adopt-A-Highway program.

Over the next several months, the court will weigh Georgia’s claim for sovereign immunity — the idea that the state is protected from civil suit or criminal prosecution — which is the key argument in the case.

Maya Dillard Smith, executive director for the American Civil Liberties Union in Georgia, said it’s the sovereign immunity claim that is especially “disheartening.”

“It will be expanding the right of the state to engage in viewpoint discrimination,” she said in a statement Tuesday to The Washington Post. “That is, the state will be given a license to refuse participation of individuals and groups whose speech the government disagrees with.

“Today it’s the KKK. Tomorrow it’s journalists, lobbyists, religious evangelicals and even Black Lives Matter.”

Georgia Department of Transportation officials were not immediately available for comment.

The Klan has been caught up in a three-year battle over free speech rights.

It stemmed from a dispute in spring 2012, when KKK members April Chambers and Harley Hanson submitted an application to claim a one-mile stretch on Route 515 in the Appalachian Mountains near the North Carolina border.

They wanted “IKK Realm of GA, Ku Klux Klan” to appear on the road sign.

“We just want to clean up the doggone road,” Hanson told the Atlanta Journal-Constitution at the time. “We’re not going to be out there in robes.”

But the state’s Department of Transportation denied their request, explaining in a rejection letter that the area had a 65 mph speed limit and was not safe for volunteers. The other issue was with their name: KKK.

“The impact of erecting a sign naming an organization which as a long-rooted history of civil disturbance would cause a significant public concern,” it said.

The Klan — with help from the ACLU — filed a lawsuit that fall in Fulton County Superior Court, requesting an injunction to stop the state from denying the permit, as well as a declaratory judgment claiming the state violated the state constitution.

The case has since bounced back and forth — making it a matter for the top court.

A trial judge issued a final order in late 2014, ruling that the state’s rejection was an unconstitutional infringement on the KKK’s right to free speech and, further, that the state could not deny applications to its Adopt-A-Highway program out of “public concern” based on the group’s history.

The state appealed it.

Georgia’s appeals court ordered the case moved to the state supreme court in November, in part because of the state’s sovereign immunity defense.

On Monday, the state supreme court court took the case.

Alan Begner, lead counsel for the Klan, said the justices heard arguments, including the state’s case for sovereign immunity and government speech.

If the state’s claim that it cannot be sued holds up in court, he told The Post, “then the Georgia constitution is gutted and is a meaningless document.”

If the KKK wins, however, Begner said the members are going straight to the state’s Department of Transportation.

“We’re going to knock on the door,” he said, “and say, ‘We’re ready for our signs and our vests and our trash bag.

“Then we’ll see.”