There are a number of defenses that you can raise to prove your innocence. Even if you seem to have infringed, there are a number of situations in which you will not be found guilty. The best ways to excuse yourself from patent infringement are to either claim that the patent is unenforceable or to claim that your infringement is permitted under patent law.

When are Patents Unenforceable?

Some of the common situations where patents are unenforceable are:

  • Patent invalidity – although an issued patent is presumed valid, you can challenge validity by offering evidence that the patentee failed to meet the patentability requirements. For example, you could produce prior art that proved the patented invention wasn’t novel.
  • Inequitable conduct – Even if the patent is valid, it may be unenforceable if the patentee was devious in getting it. If the patentee intentionally misled the patent and trademark office about material information, the patent will not be enforceable.
  • Delay in bringing suit – if the patentee unreasonably and inexcusably delayed in bringing suit from the time he learned of the infringement, he may lose his right to enforce his patent
  • Patent misuse – if the patentee uses his patent to become a monopolist or to violate anti-trust laws, or if he brings bad-faith claims of infringement, his patent may be unenforceable.

When is Infringement Permitted under Patent Law?

Some of the common situations where infringement is permitted under patent law are:

  • Implied license – an authorized sale of a patented article gives the buyer an implied license to use it.
  • First sale – an authorized sale of a patented article also gives the buyer the right to sell that particular patented article to a third party.
  • Repair – The owner of a patented article has the right to repair it, and to replace its unpatented components as they wear out. However, the owner does not have the right to completely reconstruct the article in its entirety after it has been used up.
  • Experimental use – A person can infringe upon a patent if he does so for the purposes of pure research and experimental use. Any commercial purpose for using the patented article will make the experimental use inapplicable.

Should I Consult a Patent Lawyer about Possible Defenses to Infringement?

If you are accused of patent infringement, an experienced patent lawyer or Intellectual Property lawyer can clarify the complicated patent system and let you know what defenses are available to you.