A U.S. labor board whose enforcement powers are being challenged in a series of lawsuits is set to defend itself from attacks by Elon Musk's SpaceX and Amazon.com in a conservative U.S. appeals court,

Attorneys for Amazon and Elon Musk’s SpaceX argued in a federal appeals court Monday that the National Labor Relations Board’s structure is unconstitutional, advancing a legal fight that may last into the Trump administration where Musk is expected to oversee bureaucratic cost-cutting.

Amazon and SpaceX are seeking to hamstring the National Labor Relations Board, asking a court to declare its processes for upholding labor law unconstitutional. But judges on a three-person panel appeared skeptical when the companies presented their arguments Monday.