Three new procedures for challenging the validity of granted patents were created by the AIA, effective from 16 September 2012: Post-grant review, Inter Partes review, and Covered Business Method review.
A Post-grant review (PGR) can be initiated up to nine months from the date a US patent is issued. The patent must have a priority date on or after 16 March 2013. Anyone who is not the patent owner may file a petition for PGR on the grounds that one or more claims of a patent are invalid.
Proceedings for Inter Partes review (IPR) are similar to PGR, with a few key differences: