Poland's Constitutional Tribunal has ruled that parts of a new law governing its own operation are unconstitutional.

The ruling Thursday is the latest development in a nine-month saga centered on Poland's highest legislative court.

The right-wing ruling Law and Justice party took steps after taking power last November to stack the court with its supporters and change the rules by which it can reach rulings; The European Union says the steps have weakened the rule of law.

The court said among rules that are unconstitutional is a provision giving four judges on the 15-judge court the power to block rulings for up to six months.