If you have received a letter alleging trademark infringement, it is important to look closely at the rights being asserted. Some trademarks even though registered are unenforceable trademarks.
Did you know it is possible to have a federally registered trademark in the U.S. and still not have a legitimate basis to assert trademark infringement?
Although a US company or person seeking to register a trademark with the U.S. Patent and Trademark Office needs to establish use of the trademark in U.S. commerce in order to register it, a foreign company or person that owns a trademark registration in their home country is able to register its trademark in the U.S. based solely on a foreign trademark registration, sometimes referred to as "home registration basis." This can result in a foreign company or person -- perhaps reasonably -- believing it can enforce its U.S. trademark registration against other trademarks in use in the U.S. without first establishing use of its own trademark in the U.S.
However, it is important to keep in mind the test for trademark infringement, which is whether there is a likelihood of confusion in the minds of consumers. Without actual use of both trademarks in the U.S., the foreign company or person is not likely to succeed with its claim that consumers are likely to be confused and therefore its infringement claim is likely to fail. This is why I call them unenforceable trademarks.
The easiest way to verify whether the trademark registration being asserted against you is based solely on a foreign registration or "home registration basis" is to look up the registration at the U.S. Patent and Trademark Office website using the Trademark Electronic Search System (TESS) available at http://www.uspto.gov/trademark. If the current basis information only lists "44E" in the TESS listing for the registration, or more importantly, the only basis listed under the relevant class(es) of goods or services is "44(e)" on the associated Trademark Status & Documentation Retrieval (TSDR) page, then the next question you should ask is whether the registrant is actually using the trademark in the U.S. If not, or it is not clear, there may be grounds to challenge the allegation of infringement. An experienced trademark attorney can assist in determining the best strategy to address any allegation of infringement based on the particular situation.