A Shelbyville manufacturer is seeking to cancel a trademark held by Tervis Tumbler Co., which built a $75 million business around making double-walled plastic cups.

Williams Industries Inc. of Shelbyville makes a similar product, but the business line is in danger of drying up since Tervis sent a cease-and-desist letter to a key Williams customer, Hit Promotional Products Inc. of Largo, Fla.

Williams responded with a federal lawsuit that claims Tervis had no right to trademark the horizontal lines that are featured on both companies’ transparent tumblers.

“Regardless of who thought of it first, it’s just a design that’s out there,” said Dwight Lueck, Williams’ attorney at Barnes and Thornburg in Indianapolis. “When people see those lines, they don’t think of Tervis.”

Williams makes a variety of plastic products, but the one at issue is called the Titan tumbler, which it makes for Hit. Hit suspended orders after it received a letter last month from an attorney for Tervis, based in North Venice, Fla. Tervis demanded that Hit stop selling the Titan tumblers by July 1.

The halt in business could do “substantial harm” to Williams, according to the lawsuit filed in U.S. District Court of southern Indiana.

Lueck said he could not disclose details about Williams’ sales and how they'll be affected if it loses Hit's business. Luke Williams, president of the family-owned business, could not be reached for comment Wednesday morning.

Doug Cherry, an attorney in Sarasota, Fla., who represents Tervis on intellectual property matters, said the company would not comment on litigation. Tervis hasn't yet replied to the Williams suit, filed June 27.

Tervis sells its tumblers through company stores in major tourist destinations and retailers including Bed Bath & Beyond. The tumblers usually feature team logos or other designs floating between the plastic walls.

Tervis applied in 2003 for registration of the horizontal lines as a trademark and received it in 2006. The trademark was the basis of the cease-and-desist letter that Cherry sent to Hit on June 21.

But Williams’ lawsuit alleges Tervis didn’t have a right to that trademark in the first place. The company noted that a number of companies make insulated plastic tumblers with horizontal lines. Among them is Signature USA, a Minnesota drinkware maker that’s been in business for 25 years.

Williams’ attorneys believe they can show that Signature was making its tumbler with horizontal lines in 2003, when Tervis claimed it was the exclusive user of that design.

Tervis said in a December press release that its sales have grown five-fold since 2000 and were expected to top $75 million last year. The family-owned company has expanded a Florida manufacturing plant that opened in 2005 and employs about 400 people.

Tervis, which has been in business since 1967, said in its press release that license agreements with professional and college sports teams were a factor in its growth.

Williams Industries has been in business since 1944 and manufactures a number of products, including drinkware, mouse pads, counter and floor displays, wipe-off boards, keychains, signs and decals. It specializes in molding and printing work. The company has about 160 employees, according to public documents.