Non-infringement: Your product or process is not the same as the one protected by the patent in question.

Invalidity: The patent in question is invalid as obvious or anticipated by prior art. Every patent is assumed to be valid based on the USPTO examination before it is awarded. Therefore, to invalidate a patent as obvious or anticipated requires convincing and clear evidence that prior art already exists.

Inequitable conduct: A defense of inequitable conduct asserts:

• The patent owner misled the examiner on purpose
• The patent owner withheld information they knew was important
• The patent is not valid, and no infringement can be had
• Honesty rules of some kind were broken

First Sale Doctrine: You are reselling an item legally sold to you. This defense is available because patent rights exhaust on a specific item once that item is sold.

Repair Doctrine: You are repairing a device by replacing components that are not patented. This defense does not permit you to completely rebuild an invention.

Patent misuse: The following examples are considered misuse of a patent:

• Using it to violate antitrust
• Using it to crush competition
• Using it to engage in business practices that are unethical, such as price fixing

Licensing: The patent holder granted permission or rights to use the patent to you and you have used the invention in compliance with said rights or permission.

Patent Exhaustion: The accused’s supplier upstream has legally purchased the patented invention from either the patent holder or a licensee of the same. Current laws forbid a patent holder from attempting to collect payment from multiple levels of a supply chain for a single patented invention.

Estoppel: There are two forms of estoppel:

• File Wrapper Estoppel: If the inventor disclaimed rights or admitted to any limitations of rights in their patent application, those disclaimed rights cannot be used as part of a patent infringement case.
• Equitable Estoppel: The patent holder led you to believe that there would be no enforcement of the patent. This can occur either from promises or failure to enforce. It means that the accused counted on that belief or assurances in continuing their business practices.

Experimental use: You can use a patent invention if it is related to the development of information. You can also use it if it is related to the submission of the same under Federal laws regulating the use, sale, and manufacture of drugs.