In most jurisdictions, there are ways for third parties to challenge the validity of an allowed or issued patent at the national patent office; these are called opposition proceedings. It is also possible to challenge the validity of a patent in court. In either case, the challenging party tries to prove that the patent should never have been granted. There are several grounds for challenges: the claimed subject matter is not patentable subject matter at all; the claimed subject matter was actually not new, or was obvious to the person skilled in the art, at the time the application was filed; or that some kind of fraud was committed during prosecution with regard to listing of inventors, representations about when discoveries were made, etc. Patents can be found to be invalid in whole or in part for any of these reasons.
in most jurisdictions there are ways for third parties to challenge the validity of an allowed or issued patent at the national patent office; these are called opposition proceedings it is also possible to challenge the validity of a patent in court in either case the challenging party tries to prove that the patent should never have been granted there are several grounds for challenges the claimed subject matter is not patentable subject matter at all; the claimed subject matter was actually not new or was obvious to the person skilled in the art at the time the application was filed; or that some kind of fraud was committed during prosecution with regard to listing of inventors representations about when discoveries were made etc patents can be found to be invalid in whole or in part for any of these reasons