The challenge to a federal fishing regulation that led to the Chevron doctrine's demise returned to the U.S. Court of Appeals for the D.C. Circuit on Monday.

At least two judges on the panel seemed to lean toward upholding a rule requiring boat operators to carry and pay for observers at their own expense, even after the U.S. Supreme Court's landmark decision in June telling lower courts not to defer to federal agencies' interpretations of ambiguous laws.