Three months after threatening legal action, a public relations consultant hired by the Edgartown Library Foundation to promote its annual fundraiser has filed a lawsuit in federal court against the organization claiming copyright infringement.

The complaint filed Dec. 2 in U.S. District Court in Boston by Texas-based Holiday Public Relations claims that the library foundation improperly used the slogan “Frankly, We (Heart) Our Library” to promote its Labor Day event at the Katama Air Field. It seeks an injunction, damages and attorney fees.

The 11-page complaint names the Edgartown Library Foundation as well as foundation chairman Susan Cahoon, library foundation board members Heather Cohan and Anne Vose, and Melissa Aldeborgh, identified as a freelance graphic designer.

Reached by telephone yesterday, Ms. Cahoon declined to comment based on the advice of counsel.

The complaint claims that Danielle Pendergraft, director of Holiday, created the slogan “Frankly We (Heart) Our Library” set alongside an image of a hot dog and a bun, in July 2009. These were used to promote Edgartown library fundraisers in 2009 and 2010 where frankfurters were served when Holiday had a contract with the library foundation to plan and produce the events.

After the foundation’s contract with Holiday ended in July 2011, the complaint alleges, the foundation continued to use the slogan even though Mrs. Pendergraft told members repeatedly they did not have the rights to do so. Holiday claims it has used and is in negotiations to license the slogan and image to other libraries for community events where hot dogs are served.

The complaint claims that the foundation’s use of the slogan and Holiday’s efforts to enforce its rights have injured the public relations company’s business reputation and “directly affected its ability to secure new contracts within the community.”