Idaho's highest court says the state must enforce legislation banning lucrative instant horse racing terminals after ruling that Gov. C.L. "Butch" Otter's veto of the bill was invalid.

The decision is a blow to Idaho's horse racing industry, where officials have pleaded that the machines are vital to keeping their businesses afloat.

In a unanimous decision issued Thursday, the court ruled that the ban must go into effect because Otter did not complete the veto within the required five-day time span. In Idaho, a bill automatically becomes law — even if the governor doesn't sign it — unless it is vetoed within the legal timeframe.

"This pivotal decision reaffirms that even Idaho's highest elected officials must follow the Constitution," said Coeur d'Alene Tribe Chief James Allan, chairman of the tribe that filed the lawsuit against the state, prompting the court's ruling. The tribe, which profits from its own video gaming on the reservation and faced competition from the new horse racing versions, said it was "extremely happy" with the ruling.

Secretary of State Lawerence Denney must now certify the law, which will make the machines illegal. He did not immediately return calls from The Associated Press on when he will certify it. There are currently about 250 machines installed in three locations across Idaho.