Deregulation has been the unsung economic success story of the Trump administration. Today the Labor Department adds its “joint employer” rule to the long list of deregulatory wins. When joint employment exists, two separate companies are responsible for ensuring that workers receive the federally mandated minimum wage and overtime pay. Two companies are responsible for ensuring the proper records are kept. And two companies can be taken to court if it’s alleged that those responsibilities have not been met.

Joint employment...