What are the defenses to patent infringement?
There are two basic lines of defense: non-infringement and invalidity. Non-infringement: To infringe a patent, one must practice every element of a claim. If you do not practice one or more of the elements of a claim, then you do not infringe that claim. This determination often rests on how a court interprets the language of the claims you are accused of infringing. Invalidity: Only a valid patent can be enforced. Issued patents are presumed valid, but this presumption can be overcome if prior art exists that demonstrates an invention was not novel or that it was obvious at the time the patent application was filed. Especially in the case of software and Internet business method patents, articles disclosing or describing the patented inventions may exist in trade publications that would not have been found by the patent examiner and would not have been part of the prosecution file of an issued patent on file with the USPTO. The patent holder’s failure to name all inventors may also in
