Legal Definitions - infringement test

Infringement Test

This term refers to a principle used in patent law to determine if a specific, narrower patent claim (known as a dependent claim) has been infringed, based on whether a broader, foundational patent claim (an independent claim) has been infringed.

In essence, if a product or process infringes an independent claim, it automatically infringes any dependent claim that builds upon it. This is because a dependent claim always incorporates all the features of the independent claim it refers to, plus one or more additional features. Therefore, if something contains all the elements of the independent claim, and also contains the additional elements of the dependent claim, it must necessarily infringe both.

Here are some examples:

• Example 1: A Patented Device

  Imagine a patent for a new type of bicycle. Independent Claim 1 describes "A bicycle comprising a frame, two wheels, handlebars, and pedals." Dependent Claim 2 states "The bicycle of Claim 1, further comprising a front suspension system." If a manufacturer creates a bicycle that includes a frame, two wheels, handlebars, pedals, and a front suspension system, their product clearly infringes Independent Claim 1. According to the infringement test, because their bicycle also includes the front suspension system, it automatically infringes Dependent Claim 2 as well. If it infringed Claim 1 but *didn't* have a front suspension, it would only infringe Claim 1.

• Example 2: A Patented Process

  Consider a patent for a method of preparing a specific type of dough. Independent Claim 1 describes "A method for preparing dough comprising mixing flour and water, and kneading the mixture." Dependent Claim 2 states "The method of Claim 1, further comprising adding yeast before kneading." If a bakery uses a process that involves mixing flour and water, kneading the mixture, and adding yeast before kneading, their process infringes Independent Claim 1. The infringement test dictates that since their process includes the additional step of adding yeast, it also infringes Dependent Claim 2.

• Example 3: A Software Feature

  Suppose a patent covers a data compression algorithm. Independent Claim 1 describes "A method for compressing data comprising identifying repeating patterns and replacing them with shorter codes." Dependent Claim 2 states "The method of Claim 1, wherein the shorter codes are variable-length Huffman codes." If a software company develops a program that identifies repeating patterns, replaces them with shorter codes, and specifically uses variable-length Huffman codes for this replacement, their software infringes Independent Claim 1. Applying the infringement test, because their implementation includes the specific type of codes mentioned in the dependent claim, it also infringes Dependent Claim 2.