Business and conservative interest groups that want to limit the power of federal regulators think they have a winner in the Atlantic herring and the boats that sweep the modest fish into their holds by the millions.

The 1984 decision in the case known colloquially as Chevron states that when laws aren’t crystal clear federal agencies should be allowed to fill in the details.

Supporters of limited government have for years had their sights set on the decision, which they say gives power that should be wielded by judges to experts who work for the government.

“If you’re deferring to the agency’s interpretation of the law, you’re allowing the agency to be a judge in its own case,” said Mark Chenoweth, president of the New Civil Liberties Alliance, which is representing fishermen based in Rhode Island. A second case, involving boats based in Cape May, New Jersey, is also being argued Wednesday.

The alliance, funded by conservative donors including the Koch network, says it’s “committed to cutting the administrative state down to size.”