By failing to provide notice of a registered mark, the owner cannot recover profits or damages from an infringer, unless the defendant has actual notice of the registration. Therefore, a trademark owner should always display the appropriate symbol. The proper manner to display the symbol is as a superscript at the upper right of the mark. The TM and SM symbols are used for not only potential federal trademarks but can also be used to represent a mark having rights at common law. These may include state registered marks.
Common law protects the owner of the mark but to a lesser degree than federal registration.