Late on Friday, State Supreme Court Justice Cheryl Joseph issued a temporary restraining order to stop all work on the Shinnecock Indian Nation’s electronic billboards along Sunrise Highway in Hampton Bays until the issue is resolved in court, the court’s principal law clerk, Mary Porter, confirmed this week.

The Nation, meanwhile, has already taken its case to federal court at the same time, filing a complaint against the state and its Department of Transportation officials for taking action against the federally recognized Native American tribe.

The commissioner of the State DOT filed court papers that day targeting the seven Tribal Trustees and the billboards’ owners and contractors. The papers included the request for a temporary restraining order, or TRO.

The TRO request documents state: “The state and the plaintiff’s state agency have a responsibility by law and to the people of this state to ensure that no person or entity, including a Native American tribe or their co-owner commercial advertising company, can illegally build structures on a state highway that pose significant hazards to the public at large both during and after construction.”

Tribal Trustees said in an interview Tuesday that they will assert sovereign immunity as a response to the legal action. They sent a press release on Tuesday stating that the Nation’s status “as one of 573 sovereign Indian nations in the United States” grants it immunity from the lawsuit.

The Nation was able to get its billboard along the south side of Sunrise Highway operational just hours before the TRO was issued, and Trustees said they are not sure if the order means they will be forced to shut off the advertisements.

On Friday morning, the 30-foot-tall digital screens—the entire double-sided billboard is 61 feet tall—lit up and displayed advertisements periodically throughout the day and night, continuing over Memorial Day weekend. Lance A. Gumbs, the vice chairman of the Council of Trustees, said the screen was turned off for periods of time because they are still testing its operation.

The billboard still needs some finishing touches, like landscaping work and the replacement of a temporary base, Mr. Gumbs said. The two digital screens were installed about a week ago, on May 22, on both sides of the structure. A 15-foot-tall illuminated display of the Nation’s seal was secured at the top the following morning.

The billboard along the north side has yet to see much progress and likely will not be worked on until a determination is made in court. Trustees explained that they wanted to finish one billboard before doing major work on the other.

On the same day that the papers were filed in state court, the Nation filed a complaint in the U.S. District Court for the Eastern District of New York against the State Department of Transportation, the State of New York and Marie Therese Dominguez, who was nominated this month by the governor to be the next acting commissioner of the Department of Transportation.

The next court date at State Supreme Court is scheduled for Friday, June 7, Ms. Porter confirmed.

Mr. Gumbs said that more than 70 local businesses have expressed interest in buying ad space on the billboards. East End residents have shown so much support, he added, that the Nation is planning to start a fund where people can donate money to help offset its legal expenses in fighting the legal battle.

“We’re going to eventually set up a legal fund for that, because there’s so many people that are calling about how they can donate to the cause,” Mr. Gumbs said. “We understand there are those who don’t like it, but the overwhelming support that we are getting has just been tremendous.”

Trustees also pointed out that seeing the billboard lit up has been “emotional” for many tribe members who are proud to see it representing their Nation.

“We will no longer be overlooked,” said Daniel Collins Sr., the secretary of the Council of Trustees.