An ideologically divided U.S. Supreme Court gave businesses more power to channel disputes into individual arbitration proceedings April 24.

It sided with lighting retailer Lamps Plus Inc. in its attempt to prevent its employees from pressing class claims stemming from a phishing attack.

Courts shouldn’t allow class arbitration unless an agreement clearly authorizes that type of proceeding, the 5-4 ruling said. It’s the latest in a line of Supreme Court decisions that have backed arbitration and helped companies avoid the prospect of costly class actions filed by workers and consumers.

“Neither silence nor ambiguity provides a sufficient basis for concluding...