USA Law and Practice Contributed by: Steven Lieberman, Joseph A Hynds and Jennifer P Nock, Rothwell, Figg, Ernst & Manbeck PC
3.5 Defences Against Infringement An accused patent infringer may seek to avoid liability by proving that no infringement occurred, the patent is invalid or the patent is unenforce- able. Several defences to patent infringement do not require challenging the patent itself, either by showing the accused article does not infringe or showing the use of the patent was lawful. For example, direct infringement requires all the ele- ments of the patent claim be present, so dem- onstrating missing elements in the article can avoid liability by direct infringement. Showing an implied or express licence can negate the infringement requirement of unauthorised use of a patented invention. In the medical field, gath- ering data to support an ANDA for a generic ver- sion of a patented and FDA-approved drug does not create patent infringement liability – although the filing of the ANDA may. The courts also rec- ognise a more general experimental use excep- tion to liability, but it is a very narrow exception, requiring no business motive in the experimental use. Under certain circumstances, prior com- mercial use of an invention occurring more than a year before the patent application can avoid infringement liability. Finally, infringement dam- ages are limited by law to the six years prior to the filing of the complaint, so infringement before this period would not incur liability. The accused infringer may also challenge the validity of the patent because there will be no liability for an invalid patent. The grounds for challenging the patent may include lack of pat- ent-eligible subject matter, lack of novelty, lack of enablement or written disclosure, obvious- ness of the invention, public knowledge or prior offers to sell.
The patent holder’s actions can also be the basis of a defence against infringement. Inequi- table conduct can result from improper conduct before the USPTO. Relying on a patent holder’s conduct and representations may create equi- table estoppel if the patent holder later acts inconsistently with the reliance. A patent holder that impermissibly expands its rights beyond the statutory patent grant may commit patent mis- use. Under patent exhaustion – also referred to as the first sale doctrine – the patent holder’s right to control an individual article ends after an authorised sale. In some circumstances, a patent holder’s failure to keep patents together that are subject to a terminal disclaimer may be used as a defence to patent infringement. That an accused infringer has its own patent does not, by itself, provide a defence to an infringement claim. Standard-Essential Patents Some patent holders may have standard-essen- tial patents (SEPs). An SEP is a patent that cov- ers technology that is considered essential to an industry standard. These SEP holders gen- erally have an obligation to license these pat- ents on fair, reasonable, and non-discriminatory (FRAND) terms. If the SEP holder fails to offer a potential infringer FRAND terms, the accused infringer can assert the breach of FRAND obliga- tions as an affirmative defence in a subsequent infringement action. 3.6 Role of Experts Parties may submit expert reports in connec- tion with the claim construction process to assist the court in construing disputed terms. Parties almost always rely on expert reports and expert testimony in connection with infringement, inva- lidity and damages issues. Experts are especially effective when a case involves a jury because a
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