The U.S. Supreme Court on Monday let stand an Illinois system of issuing concealed carry permits that gun owners had complained violated their constitutional rights.

The court did not explain its decision, saying only that it would not interfere with the decision by the 7th U.S. Circuit Court of Appeals backing the state’s requirements for obtaining a concealed-carry license.

Illinois was the last state in the nation to allow concealed carry permits after a 2012 ruling by the same appeals court that state’s prohibition was unconstitutional under the Second Amendment right to bear arms. State lawmakers enacted the Firearm Concealed Carry Act after that court ruling.

After state officials established a system to handle the applications, gun owners who were denied permits complained that they were given no explanation why they were turned down.

The state police have since issued “emergency rules” that called for the board to notify applicants of reasons why law enforcement had objected to applications and the state amended its regulations.

A gun owner who had sued in another case ultimately agreed to its dismissal after he was able to obtain additional information about his denial and to provide a response, and his application was subsequently approved, according to the National Rifle Association’s Institute for Legislative Action in a 2014 article.

In a second lawsuit, the gun owners argued that, despite requiring the review board to explain decisions to deny applications, the state’s system still violated their due process rights.

But in June of 2016, the appeals court agreed with the state’s new requirements, which led to the Supreme Court’s decision.

Richard Pearson, executive director of the Illinois State Rifle Association, said that while the ruling ends one avenue of legal challenge to the state’s system, there still may be others.

“It still takes some people forever to hear back on their applications,” he said. That could prompt a lawsuit, he said.