The U.S. Supreme Court on Wednesday refused to overturn a key precedent that has been the target of business groups and conservatives who want to sap the power of federal regulators.

The court rejected requests to overrule Auer v. Robbins, a 1997 decision that directs courts to defer to an agency’s “reasonable interpretation” of its own ambiguous regulations. The majority also was asked to overturn a related 1945 precedent, Bowles v. Seminole Rock & Sand.