Thanks to the doctrine of fair use, a company can use another’s trademark without consent in certain circumstances—including some types of marketing. That means a company could use another firm’s carefully honed image to call attention to its own products. Think of it as “judo brand marketing”—leveraging a larger business’s assets to your own company’s advantage.

Illustration by Jason Schneider

It can work in a number of ways. For instance, a company could develop a product that’s compatible with a better-known item, such as a line of replacement blades for a popular razor, and then use the famous name prominently in advertising. A company might also run ads that compare its product with a much bigger brand—or try to get people talking by mocking a rival’s better-known mascot.

These tactics can be risky. There are limits to fair use, and companies can be sued even if they handle another company’s brand identifiers, such as logos and mascots, carefully. The brand owner might charge outright infringement of its trademark or claim that the marketer is diluting the value of its brand. Most of these cases end with a simple injunction against using the marketing tactics. But marketers can get hit with steep damages if they do something blatantly illegal, like trying to trick people into thinking they make a competitor’s product.

With that in mind, here’s a look at some popular judo-brand-marketing tactics—and how to stay well within the law when using them.

EXTENDING THE BRAND

Brand extensions are a popular tactic among companies. Putting out a somewhat different version of a well-known product, such as laundry detergents with added bleach or fabric softener, can be much less risky and costly than trying to build up a new brand from scratch.

But brand