Common Law Trademark Rights
Common law trademark rights are possessed by the person or entity that first used an unregistered Trademark. These rights, however, can only be enforced in the geographic area where a party uses the Trademark.
Therefore, if another party, e.g., a competitor, is the first to use the Trademark in a different location, its Common Law Trademark rights can prevent the party in the other location from expanding into that market.
The first user of a Trademark may have its common law rights preserved even if another party obtains federal registration for the same mark. This though, requires proof of an earlier date of first use.