WASHINGTON (CNN) - A small Kentucky sex shop has won a victory in court against world-famous lingerie retailer Victoria's Secret in a case testing the limits of economic harm to brand names.

The Supreme Court on Tuesday unanimously ruled Victor's Little Secret did not infringe on the trademark held by the similar sounding Victoria's Secret.

The question involves the legal standard called "dilution," which the federal government interprets as "the lessening of the capacity of a famous mark to identify and distinguish goods and services."

Writing for the court, Justice John Paul Stevens concluded, "There is a complete absence of evidence of any lessening of the Victoria's Secret mark's capacity to identify and distinguish foods or services sold" in its stores or through its catalogs.

Some of the Victoria's Secret line for Valentine's Day

The justices agreed there needs to be more objective evidence of economic harm than merely whether the public would confuse a disputed mark with another, more famous mark. "Use of the name 'Victor's Little Secret' neither confused any consumers or potential consumers, nor was likely to do so," Stevens wrote.

But the justices offered no clear guidelines for companies to prove their brand name was harmed. Stevens, in fact, noted the difficulties such companies face, saying "consumer surveys and other means of demonstrating actual dilution are expensive and unreliable."

The facts involve a Kentucky sex shop once called Victor's Secret that continues to sells "adult novelty" and "wild outfits." The owners of the mom-and-pop store claim the name was inspired by Victor Moseley's desire to keep the business secret from a former employer. Nevertheless, the couple was sued by Victoria's Secret, the big Columbus, Ohio-based lingerie seller, which claimed unfair competition and trademark infringement. The store did change its name to Victor's Little Secret to avoid a lawsuit, but to no avail.

A federal appeals court upheld a lower court ruling, affirming trademark infringement by saying the name Victor's Little Secret would make the public think of the well-known brand. "While no consumer is likely to go to the Moseleys' store expecting to find Victoria's Secret's famed Miracle Bra, consumers who hear the name 'Victor's Little Secret' are likely automatically to think of the more famous store and link it to the Moseleys' adult toy, gag gift, and lingerie shop," the opinion read.

Victor Moseley and his wife Cathy -- the store is now called Cathy's Little Secret -- claimed Victoria's Secret does not have a "distinctive quality" because "secret" is used by many lingerie stores and companies as part of their advertising.

It is unclear whether the Moseleys will now go back and change their store to its original name.

The case is Moseley v. Victoria's Secret Catalogue (Docket number 01-1015).

Victoria's Secret is a unit of Limited Inc. (LTD: down $0.24 to $11.63, Research, Estimates)