Doctrine Of Equivalents in Patent Infringement Claims

Doctrine Of Equivalents in Patent Infringement Claims

September 27, 2022
Walker Weitzel
Patent Law , Patent Learning


Patent infringement criteria have clearly been defined under the 35 US code 271 to protect patentee rights if their patent invention has been copied or used without their permission. Apart from the visual examination, the courts use the Doctrine of Equivalents test to examine the infringed patent and provide patentees with the right to claim compensation.

This protects patented inventions from being infringed by making slight variations to the original product to sell or use as a new invention. The DOE applies function, result and performance tests to evaluate and determine if the product patent has been infringed upon. 

The case below explains the Doctrine of Equivalents and its application to grant summary judgment for a patent infringement case.

Depuy Spine, Inc. v. Medtronic Sofamor Danek, Inc. 2008-1240 (Fed. Cir. 2009)

Depuy Spine accused Medtronic of infringing its patent number 678 for polyaxial pedicle screws used in spinal surgeries. The court granted summary judgment in favor of Depuy Spine for patent infringement under the doctrine of Equivalents.

Medtronic defended their appeal based on three arguments; their screws were not sphere-shaped, did not use a “compression member”, and were not “pressed against” during insertion like patent 678. The first two motions were denied, whereas the third one was granted because the doctrine of Equivalents did not apply to it. 

The Court stated that even if the shape of the screw was different, it still provided the same function to apply a compression force to the screw, thereby infringing upon the patent according to the “means plus function” patent law


The courts use various methods of determining the validity of patent infringement to ascertain the claims in a patent application. The appearance and features of patented inventions are not the only factors applied in infringement claims. The Doctrine of Equivalent serves as a method to access the functionality, result, and performance of the patents in infringement cases to ensure a fair decision. 

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