The purpose of the supplemental register is to allow for easier registration of international trademarks. Before you can apply for an international trademark, you must have a valid domestic trademark. In the United States, it is considerably more difficult to register a trademark than in other countries. The supplemental register provides trademark applicants an option for gaining domestic registration for marks that may not be accepted on the principal register so that the applicant can seek international registration.
Certain legal presumptions are available to a trademark holder in the principal register that are not available to trademark holders in the supplemental register. For example, holders of a trademark on the principal register can use their trademark registration certificate as prima facie court evidence that their mark is valid. Unfortunately, a trademark registration certificate on the supplemental register does not serve as evidence of validity, and the holder will be forced to introduce evidence in court as to the validity of the trademark.
Use in Commerce
When applying for a trademark on the principal trademark register, it is possible to present an application to the United States Patent and Trademark Office before the mark has actually been used in commerce. This is known as an intent-to-use application. However, there is a rule that any marks in supplemental register must actually be already used in commerce, so there are no intent-to-use applications on the supplemental register.
Marks on the principal trademark register are granted many protections not available to mark holders on the supplemental register. For example, principal mark holders have the ability to bring criminal charges against an infringer, and they may contact U.S. Customs in order to stop the importation of counterfeit goods. However, due to the limited protection granted to marks on the supplemental register, these marks don't have these types of privileges.