What Happened

You don't have to make or sell the entire infringing product to be liable for patent infringement. If you sell components specifically designed for an infringing use, you can be liable for "contributory infringement." If you encourage others to infringe, that's "induced infringement." Both are real forms of liability.

Why It Matters

Contributory infringement requires three things: (1) you sell a component, (2) that component is especially made or adapted for infringing use, and (3) it's not a staple article of commerce suitable for substantial non-infringing use. Think of it this way: if you sell a part that only makes sense in an infringing product, you're on the hook.

Induced infringement is different. Here, you're actively encouraging someone else to infringe—through marketing materials, instructions, or direct communications. The key is intent: you have to know about the patent and intend to cause infringement.

Both theories let patent owners go after companies in the supply chain, not just the final seller. This is important when the direct infringer is small, overseas, or judgment-proof. Going after the component supplier or the company providing instructions can be more effective.

What You Should Know

If you're selling components, do an infringement analysis. Can your product be used in non-infringing ways? Document those uses. If you get notice of a patent, take it seriously—ignorance won't protect you from induced infringement claims.

If you're a patent owner, consider whether contributory or induced infringement theories apply. They can expand your target list and increase your leverage.

The law recognizes that infringement isn't always straightforward. Sometimes the real culprit is the company enabling it, not just the one doing it.