Trademark law. This is the principal list on which distinctive trademarks and service marks that are approved for federal regulation are placed and which acts as notice to third parties that a mark is protected. After five successive years where a mark is not challenged, it becomes permanently established and not able to be legally challenged. This also makes it easier to establish an infringement lawsuit for intentional infringement, which provides for larger damages and potential attorneys fees. For comparison, see the Supplemental Register.