In the United States, the Supplemental Register is a listing of trademarks and service marks maintained by the United States Patent and Trade Office (USPTO). Entries in the Supplemental Register enjoy some legal protections, but not as many as those provided to those on the Principal Register. Since some protection is viewed by businesses as better than none, companies that cannot register something on the Principal Register may opt to apply to the Supplemental Register.
The concept of the Supplemental Register was developed in 1946. While companies can apply directly to be listed in it, it is more common for an application to the Principal Register to be denied with a note that the company can resubmit the application to the Supplemental Register. Products do not qualify for the Principal Register if they are not sufficiently distinctive, but they may be eligible for the Supplemental Register.
When something if registered on the secondary register of trademarks, as it is also known, it has the capability of being used to distinguish services and products, but it is not necessarily used in that way. Once registered, it is possible to use the registration to block attempts to register similar trademarks or service marks on the grounds that they would be confusing or misleading. However, the owner of a product on the Supplemental Register cannot claim exclusive rights to use it and also cannot do things like blocking imports of counterfeit items.
It is possible to file a trademark infringement suit in court for an item that is listed on the Supplemental Register. Unlike items on the Principal Register, however, notice is not provided to the public about the registration of the item. Conversely, people cannot contest an application for the Supplemental Register, because no public notice is provided about applications. These differences in protection and legal status mean that people may not be able to be as proactive about protecting items on this secondary register, but they are not completely powerless in cases of infringement either.
Items do not automatically move from the Supplemental Register to the Principal Register, but it is possible for them to do so with another application. If an item acquires demonstrable secondary meaning and becomes uniquely associated with a given product or service, an argument for placement in the Principal Register can be made. Trademark attorneys can assist people with the process of filing service mark and trademark applications and determining which register is appropriate in addition to following up with applications in the future.