It's a serious case of trademark madness: food-delivery startup DoorDash has been sued by one of the restaurants that it buys food from, In-N-Out Burger.

One might think the West Coast burger chain would be at least tolerant of DoorDash and its competitors, companies that could expand the market for prepared meals at no extra cost or risk to the restaurants. But In-N-Out lawyers make the case that DoorDash is actually violating its trademark rights with its unlicensed delivery business.

In the complaint (PDF), In-N-Out attorneys claim that DoorDash uses an "Imitation Logo" of In-N-Out on its website, which "is intended to, and has, confused consumers as to Defendant's authority to delivery Plaintiff's food items." They charge DoorDash with trademark infringement, dilution, and unfair competition. The lawsuit was filed on November 6 and first reported yesterday by TMZ.

Lawyers for In-N-Out say DoorDash's delivery vehicles aren't compliant with the California Retail Food Code, and In-N-Out would never authorize DoorDash "or any other entity to deliver its food products to consumers without the necessary food handling licenses and food safety procedures in place."

In-N-Out explained to the Eater blog its belief that consumers would be confused by another company delivering its burgers:

DoorDash is using our food and trademarks in a way that implies we have some kind of partnership or agreement with them, when that is not the case. We have asked DoorDash several times to stop using our trademarks and to stop selling our food. Unfortunately, they have continued to prominently use our trademarks and serve our food to customers who believe that we are responsible for their delivery. Prior to filing the lawsuit, we tried contacting them several more times but they never responded to our phone calls or letters.

DoorDash responded to press inquiries only by saying that the company has "various relationships with different merchants."

Trademark cases hinge on whether the defendant's use of a protected mark will create a "likelihood of confusion" among customers. So would burger-buyers somehow think that their DoorDash driver actually works for In-N-Out? That scenario is so unlikely that In-N-Out doesn't even try to argue it. Rather, the burger chain alleges that use of its logo will cause "actual and prospective customers ... to believe that Plaintiff has approved or licensed Defendant's use of its marks, or that Plaintiff is somehow affiliated or connected with Defendant or its services or has been authorized by Plaintiff to deliver Plaintiff's food products."

In other words, customers might think that the two companies struck some kind of deal when really they haven't. In-N-Out is looking for a type of consumer "confusion" that's not about the source or goods of a product but about the legal relationship between the two companies. If consumers are pulled off the street and surveyed about those relationships—and it's likely that is exactly how In-N-Out will proceed to prove its case—confusion will seem to abound.

The relevance of that "confusion" seems questionable, though. Fighting over what licensing the public may believe is required is a huge stretch of trademark's consumer-protection function, suggesting that if consumers don't draw the correct legal conclusion, someone is violating the law. That type of confusion will abound forever.

Third-party delivery services are well understood. If the burgers come cold, consumers savvy enough to download DoorDash's app will be savvy enough to blame DoorDash for their unhappy meal.