By Blake Brittain

Feb 18 (Reuters) - The maker of popular Stanley beverage containers was hit with a lawsuit from U.S. toolmaker Stanley Black & Decker SWK.N on Tuesday, accusing it of misusing the "Stanley" name to gain "viral success."

The lawsuit in Connecticut federal court against Pacific Market International said its Stanley-branded cups confused customers into thinking the two companies are affiliated and broke a decades-long coexistence agreement.

Stanley Black & Decker asked the court for an order blocking PMI's use of the "Stanley" name and an unspecified amount of monetary damages.

The lawsuit said PMI has sold "hundreds and hundreds of millions (if not billions) of dollars of STANLEY-branded merchandise in violation of the parties' agreement." Sales of Stanley cups skyrocketed after the brand gained popularity on social media beginning in 2022.

Spokespeople for PMI did not immediately respond to a request for comment on the lawsuit. An attorney for Stanley Black & Decker declined to comment.

Toolmaker Stanley was founded in 1843. The lawsuit said Stanley and PMI's predecessor Aladdin first signed a contract in 1966 that limited Aladdin's use of the "Stanley" name to "insulated containers adapted to keep their contents hot or cold."

According to the complaint, a 2012 agreement signed following PMI's "repeated non-compliance" with the 1966 contract required it to include its full corporate name with "Stanley" and not use "Stanley" as a "company name, division or proper noun."

The lawsuit said that PMI violated its contracts by rebranding as Stanley 1913 and using "Stanley" as a standalone name on its products and in advertising. The complaint also said that Stanley Black & Decker faced harm to its reputation from "several waves of negative press" about alleged risks of lead poisoning and burn hazards from Stanley cups.

The case is Stanley Black & Decker Inc v. Pacific Market International LLC, U.S. District Court for the District of Connecticut, No. 3:25-cv-00243.

For SBD: Kevin Lamb, Louis Tompros and Omar Khan of Wilmer Cutler Pickering Hale & Dorr

For PMI: attorney information not yet available

(Reporting by Blake Brittain in Washington)