How to read a patent claim

The method

Take the independent claim and split it at every comprising, wherein, configured to and each semicolon. Number the fragments. Each fragment is a feature.

Now ask, of the product in front of you: does it have feature 1? Feature 2? All the way down. If any answer is no, that claim is not infringed - however similar the products look, and whatever the description says.

That is the whole exercise, and it is the same one a court does. The description and the drawings help you understand what the words mean; they do not extend the claim.

Two traps

Comprising is open. A claim to a device comprising A, B and C is met by a device with A, B, C and D. Adding features does not avoid infringement.

Consisting of is closed. That wording, where it appears, excludes additional elements - so the same product might not infringe.

Also watch for functional language: a component configured to do something is met by anything that does it, which is usually broader than it first appears.

What to actually do

• Split claim 1 into numbered features and test each one.
• One missing feature means no infringement of that claim.
• Comprising is open-ended; adding features does not help you.
• Read the description to understand the words, not to widen or narrow the claim.