Houston's convention bureau is suing the operators of a popular local convention over the use of "Space City" in its name, claiming it infringes on a 12-year-old trademark.

The convention in question, Space City Comic Con, also happens to compete with a similar event that is half-owned by the Greater Houston Convention and Visitors Bureau itself. The bureau acquired a 50 percent stake in the more established Comicpalooza last September, spokesman A.J. Mistretta said.

Both events bring in television and film stars for appearances that attract thousands of autograph buyers. Fans come dressed as their favorite characters from science fiction, anime and super-hero fantasies to browse exhibits, purchase items from vendors and play video and table-top games. The fests charge comparable admission fees.

The convention bureau, which declined to discuss the case for this story, may believe it's losing money if people are confused over which show is sponsored by the economic development arm of Houston, said Betsy Gelb, professor of marketing and entrepreneurship at the Bauer College of Business at the University of Houston. She agreed that if it managed to trademark "Space City," it has every reason to defend it in court.

But, she added, "Does it help your image to do this?"

Comicpalooza founder John Simons referred all questions about the lawsuit to the convention bureau. Space City Comic Con did not return requests for comment.

Houston has billed itself "Space City," a boastful nod to its founding role in U.S. space exploration, since the 1960s. Over the decades, dozens of local companies from plumbers to construction outfits to tattoo parlors have used the moniker as part of their name. But they are not affected by the trademark registered by the convention bureau in 2004, said Charles S. Baker, an intellectual property lawyer with Locke Lord in Houston who is representing the bureau in its lawsuit.

The trademark is narrowly constructed and applies solely to efforts that promote tourism, business and conventions in the greater Houston area, Baker said.

'Star Trek' stars

Space City Comic Con, which grew rapidly after starting in a hotel lobby in 2012, returns to NRG Center this Memorial Day weekend. Among the stars coming out to meet fans are original "Star Trek" star William Shatner and Marina Sirtis, a veteran of more recent "Star Trek" fare.

Comicpalooza, which reportedly drew a crowd of more than 45,000 to the George R. Brown Convention Center last year, begins three weeks after Comic Con, with actress Kate Beckinsale of the "Underworld" franchise, author Sherrilyn Kenyon and others. The event traces its local roots here to a small gathering in 2008, but the convention bureau says it has grown to become the second-largest pop-culture event in Texas, behind Austin's South by Southwest, and claims it generated some $20 million in economic impact from spending in hotels, restaurants and clubs.

The convention bureau claims in its lawsuit in federal court in Houston that through its promotional efforts, "Space City" has become widely known in the United States, and that Space City Comic Con is causing "irreparable harm" by using the trademarked name.

The bureau is seeking a court order to force the show to stop using "Space City." The lawsuit also would require the company to give up any profits earned from using the trademark and stop competing unfairly against the bureau.

Baker said the bureau asked Space City Comic Con to stop using "Space City" in exchange for an agreement not to sue.

Mistretta said the bureau would not say how much the board invested in Comicpalooza for the 50 percent ownership stake. The bureau became part of the quasi-public Houston First in 2014. Since then, its chief source of income is dues from its 1,200 members, a group which primarily includes hotels, restaurants and other hospitality-related businesses.

Baker acknowledged that having dueling comic conventions has become a "competitive situation." But he also noted the bureau isn't trying to exclude similar character-related fantasy events. He pointed to the recent Japanese cultural convention Anime Matsuri at the convention center.

One possible line of defense for Space City Comic Con is to prove that "Space City" is a generic term that has become synonymous with Houston, said Bruce Patterson, intellectual property lawyer with Patterson and Sheridan in Houston.

The bureau also has to prove "Space City" is famous, said Amanda Greenspon, trademark lawyer with Munck Wilson Mandala in Dallas.

"It's not just enough to be famous in Texas. You have to be famous around the country, she said. "I don't know if 'Space City' is famous in Arkansas, North Dakota or New York."

In its lawsuit, the bureau said it first learned in November that Space City Comic Con would be hosting its convention in May at NRG in Houston.

'Special niche'

Baker said he can't explain how the bureau didn't know about the show before then, suggesting that perhaps it wasn't aware of the booking activities of the Harris County-owed facility.

"Everyone has their own special niche," he said.

Baker said the bureau learned about the show last year, but too late to take legal action. Bureau officials assumed it was a one-time event, he said, adding that Space City Comic Con had operated under other names in previous years.

However, a Google search revealed that "Space City" has been part of the company's name since 2012.