Hello Jen,
I have run your inquiry by Brian Hall, an attorney here at Traverse Legal who regurarly handles trademark and copyright matters. Here is his reponse:
First things first, the (c) means it is protected by copyright. Anyone claiming copyright protection can you use the (c) symbol. The TM symbol pertains to trademark protection, which is a different kind of intellectual property than copyright. Anyone claiming common law trademark protection can use the TM symbol. However, only the owner of a trademark registered with the United States Patent and Trademark Office (USPTO) may use the registered (R) symbol. A gagline typically can protected by trademark.
That said, you should be very careful about using a tagline that may subject you to claims of trademark infringement. Trademark infringement occurs when the use of a mark creates a likelihood of confusion with the mark of another. To determine whether or not your proposed tagline would infringe upon the more established company's tagline requires a detailed analysis of the approximately nine non-exhaustive factors that are part of a likelihood of confusion analysis - the two most important being similarity of the marks and similarity of the goods/services used in connection with the marks. You should consult with a trademark attorney before you proceed who can provide legal advice and guidance.
Jen, I hope this information is helpful.
Pat
Jen Udan
paralegal1
jumeira123