Rather than defend against a threatened trademark lawsuit, a California-based maritime-news website has now stopped selling T-shirts with the historic shipping icon known as the Plimsoll Line

"Yes, we got feedback from a few lawyers, and they all agreed that while we have a very strong case, our profits on those items are a fraction of the cost of a legal defense," gCaptain's owner, John Konrad, emailed Ars. "They suggested we save the money and remove the items to comply with the request... so we did. 😢"

He added that the company acceded to the demands brought on behalf of Plimsoll Gear, a company holding a trademark on the Plimsoll Line for T-shirts and other items. gCaptain stopped selling its Plimsoll T-shirts on May 20.

As Ars reported previously, ships around the world have had the small circular icon emblazoned on their hulls for well over a century.

The graphic, designed by Samuel Plimsoll, shows whether a ship is overloaded and is at risk of sinking. If someone looking at a ship can see the horizontal line, the ship isn't overloaded. If they can't see the line, there might be a problem. Additional horizontal lines are sometimes added to account for variability across different oceans.

Under the United Kingdom Merchant Shipping Act of 1876, the mark became mandatory on British ships, and in the ensuing decades it became standard worldwide.

In 2008, a North Carolina couple that included retired merchant mariner Charles Leeuwenburg founded a company called "Plimsoll Gear," inspired by Plimsoll's story.

The company registered a trademark with the United States Patent and Trademark Office, seemingly claiming the Plimsoll Line as its own for the purposes of emblazoning it on clothing, coffee mugs, and other items.

Plimsoll Gear's attorney, E. Eric Mills, did not immediately respond to Ars' request for comment.

This appears to be at least the second time that threatened litigation ultimately has been successful for Plimsoll Gear. Roman Mars, the host of the 99% Invisible podcast, told Ars on Twitter that he received a similar demand letter from Plimsoll Gear and complied with demands to halt further sales.

Jennifer Rothman, a professor at Loyola Law School in Los Angeles, emailed Ars to say that ultimately deciding not to head to court is "common."

She wrote:

As of 2007, the approximate cost of trademark litigation through trial ranged from several hundred thousand dollars to a million dollars... That makes it hard for individuals and smaller companies to risk a court battle, even if they are on the right side of the law. Often a well-written reply letter and a social media campaign can get a trademark bully to back down, but when push comes to shove, it usually is cheaper to back off than to litigate.

Another law professor, Annemarie Bridy of the University of Idaho, lamented gCaptain's situation.

"It's a shame, really, to see people with meritorious defenses give up solely because they can't afford their day in court," she emailed Ars. "But that's how trademark bullying and IP trolling work. Right holders know that it's much cheaper and less stressful for an accused infringer to capitulate or settle than it is to try to win a case in federal court."

Daniel Nazer, a lawyer with the Electronic Frontier Foundation, agreed that situations like this are "unfortunate."

"The cost of defense, even for a small case, can be hundreds of thousands of dollars," he emailed Ars. "And while I think gCaptain should win, it's hard to guarantee that the court will reach the right result. The expense and uncertainty allows trademark bullies to squelch creativity and competition."

Federal court records show that, to date, Plimsoll Gear has never filed a lawsuit.