Defenses to Patent Infringement under Intellectual Property
1. Non-Infringement
The defendant argues that their product or process does not fall within the scope of the patent claims.
Literal Non-Infringement: The accused device or process does not contain every element of the patent claim exactly.
Doctrine of Equivalents: Even if not literally infringing, the accused product is not equivalent to the patented invention.
📌 Example:
In a case where a patent covers a specific chemical process, the defendant shows their process differs sufficiently in steps or chemicals used, so no infringement occurs.
2. Invalidity of the Patent
The defendant challenges the validity of the patent itself, arguing the patent should never have been granted because:
The invention was not novel (already known before the patent).
The invention was obvious to someone skilled in the field.
The patent lacks sufficient description or clarity.
The invention is not patentable subject matter.
📌 Example:
If a patent claims a machine that was previously described in a public publication, the defendant can argue the patent is invalid due to prior art.
3. Patent Exhaustion (First Sale Doctrine)
Once the patent owner sells a patented item, their control over that specific item ends, and the buyer is free to use or resell it without infringement claims.
Applies only to the specific product sold.
Does not allow making new patented products without permission.
📌 Example:
If a customer legally buys a patented smartphone, they can resell it without infringing the patent.
4. Experimental Use Exception
Use of the patented invention solely for experimental or research purposes and not for commercial gain may be exempt from infringement.
Typically limited and narrowly interpreted.
📌 Example:
A university researcher uses a patented compound in a laboratory experiment without commercial intent.
5. Prior Use Defense
If the defendant can prove they were using the invention before the patent application date, they may be allowed to continue using it.
Limited to the scope and nature of prior use.
📌 Example:
A company demonstrating continuous use of a manufacturing method prior to the patent filing can claim a prior user right.
6. License or Authorization
If the defendant obtained a license or permission from the patent owner, the use is lawful.
Can be express or implied.
📌 Example:
A software company licenses patented technology from the patent owner and therefore is authorized to use it.
7. Inequitable Conduct
The defendant may argue the patent owner acted unethically during the patent application process, such as withholding material information or misleading the patent office.
If proven, can render the patent unenforceable.
Summary Table
| Defense | Description | Example Scenario |
|---|---|---|
| Non-Infringement | Accused product/process does not meet patent claims | Different method or design |
| Invalidity | Patent should not have been granted | Prior art or obvious invention |
| Patent Exhaustion | Patent rights exhausted after first sale | Reselling a patented product |
| Experimental Use | Use for research only, not commercial | University lab experiments |
| Prior Use | Use before patent filing date | Manufacturing method in use beforehand |
| License/Authorization | Permission granted by patent owner | Licensed software use |
| Inequitable Conduct | Unethical behavior invalidates patent | Withholding info from patent office |
Conclusion
Patent infringement defenses help ensure only valid and fairly granted patents are enforced and protect users who do not unlawfully exploit patented inventions. They also encourage innovation by allowing research and recognizing prior use.
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