Understanding The doctrine of purposive construction

 The doctrine of purposive construction

The doctrine of purposive construction is a principle in patent law that emphasizes interpreting patent claims in a way that reflects the purpose or intent behind the invention, rather than just relying on a strict, literal reading of the wording of the claims. This approach is typically used to determine whether a patent’s claims are valid and how they should be interpreted in the context of infringement disputes.

 

Key Aspects of the Doctrine:

Focus on the Inventive Concept: The core idea is to understand what the inventor was trying to achieve with the invention, rather than getting caught up in technicalities of the language used. Courts or patent offices will seek to determine the underlying inventive concept or technical contribution behind the patent, even if the claim language is broad, ambiguous, or might seem to cover something different at first glance.

 

Contextual Interpretation: Under purposive construction, the interpretation of patent claims takes into account the context of the patent as a whole, including the specification (the written description) and the patent’s objectives, along with any relevant background knowledge that would have been understood by someone skilled in the relevant technical field.

 

Skilled Person Test: The interpretation of the claim is made from the perspective of a "person skilled in the art" (PSA) — that is, someone with a reasonable understanding of the technology or field in question at the time the patent application was filed. This person would look at the claims in light of the problem the invention was designed to solve and the technical solutions it offers.

 

Avoiding Narrow Literal Interpretations: Purposive construction prevents a narrow, literal interpretation of patent claims that may unduly limit the scope of the patent or allow an infringer to escape liability due to technicalities. This is particularly important in cases of claim construction during litigation, where courts determine whether a product or process infringes a patent.

 

Legal Basis and Evolution:

The doctrine of purposive construction was most famously articulated in the UK case of Catnic Components Ltd v Hill & Smith Ltd (1982), where the House of Lords ruled that patent claims should be interpreted according to their purpose, rather than their exact wording.

 

Another landmark case was the UK Supreme Court's decision in Regeneron Pharmaceuticals v Kymab (2017), which reaffirmed the use of purposive construction. In this case, the court stated that the skilled person should understand the claims in the context of the patent’s description and the problem the patent aims to solve.

 

Importance in Patent Litigation:

Broader Claim Protection: By interpreting claims with purposive construction, patent holders are given broader protection. Courts may find infringement even if the exact words of a claim are not mirrored in the allegedly infringing product or process, as long as the alleged infringement achieves the same inventive purpose or technical result.

 

Flexibility: The doctrine allows for flexibility in how claims are construed, ensuring that patents can cover equivalent technologies or methods that solve the same problem but might not use the exact same language or approach as the original claims.

 

Prevention of Unjust Technicalities: It prevents infringers from exploiting minor differences in wording to avoid infringement, making it harder for others to design around a patent by making insignificant changes.

 

Example:

Imagine a patent for a "device that improves the efficiency of a water pump by reducing energy consumption." If the claims of the patent are written in a way that specifically mention "a reduction in the amount of electrical power required," a purposive construction approach would allow a court to interpret the claims in a broader sense. For example, if an accused infringing device uses a different method to reduce power consumption (such as using less water to achieve the same result), it could still infringe under the purposive construction doctrine because it addresses the same inventive purpose — improving efficiency by reducing energy consumption — even though the exact means differ.

 

Summary:

The doctrine of purposive construction is crucial in patent law for ensuring that claims are interpreted in a way that reflects the true inventive concept, rather than being confined to a narrow, literal interpretation. It offers greater flexibility and protection to patent holders, preventing potential infringers from avoiding liability based on technicalities or subtle differences in wording.

 

This approach is now widely recognized in jurisdictions such as the UK, the EU, and increasingly in other common law systems, especially in patent litigation.

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