	Introduction

P.L. 112-29 , the Leahy-Smith America Invents Act, or "AIA," arguably made the most significant changes to the patent statute since the 19 th century. Among other provisions, the statute introduced into U.S. law a first-inventor-to-file priority rule, an infringement defense based upon prior commercial use, and assignee filing. The legislation prevented patents from claiming or encompassing human organisms, limited the availability of patents claiming tax strategies, and restricted the best mode requirement. The AIA also made notable reforms to administrative patent challenge proceedings at the U.S. Patent and Trademark Office (USPTO) and to the law of patent marking. Passage of the AIA was preceded by several years of legislative debate about the current workings and future direction of the U.S. patent system. The Leahy-Smith America Invents Act

		First Inventor to File

The AIA shifted the U.S. patent priority rule from the previous "first-to-invent" principle to the global norm of the "first-inventor-to-file" principle. Conditions for patentability; novelty
(a) NOVELTY; PRIOR ART.—A person shall be entitled to a patent unless—
(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention; ....
(b) EXCEPTIONS.—
(1) DISCLOSURES MADE 1 YEAR OR LESS BEFORE THE EFFECTIVE FILING DATE OF THE CLAIMED INVENTION.—A disclosure made 1 year or less before the effective filing date of a claimed invention shall not be prior art to the claimed invention under subsection (a)(1) if—
(A) the disclosure was made by the inventor or joint inventor or by another who obtained the subject matter disclosed directly or indirectly from the inventor or a joint inventor; or
(B) the subject matter disclosed had, before such disclosure, been publicly disclosed by the inventor or a joint inventor or another who obtained the subject matter disclosed directly or indirectly from the inventor or a joint inventor.... 
An example may clarify the operation of the grace period post-AIA. The Patent Act also addressed the issue of "false marking." The AIA also allowed for "virtual marking." This circumstance is termed "willful infringement." In particular, the AIA (1) replaced the previous inter partes reexamination system with inter partes review proceedings; (2) introduced a new proceeding titled "post-grant review"; (3) established a new supplemental examination procedure; and (4) created a new transitional post-grant review proceeding for the review of the validity of certain business method patents. The ability of members of the public to cite to the USPTO information that may be pertinent to the validity of a granted patent has been augmented under the provisions of the AIA. Following the 1999 legislation, the USPTO began to publish many pending patent applications. The AIA additionally stipulated fees for patent services provided by the USPTO. For example, the fees for filing a patent application and for the issuance of an approved application were $300 and $1,400 respectively; the new fees are $330 and $1,510. However, violation of the best mode requirement no longer forms the basis for an accused infringer's defense to a charge of patent infringement during enforcement litigation or post-grant review proceedings. The approach embodied in the AIA keeps USPTO use of fees within the appropriations process, but mandates that any excess fees be used only to fund USPTO activities.
Following several years of legislative discussion concerning patent reform, the Congress enacted P.L. 112-29, signed into law on September 16, 2011. The Leahy-Smith America Invents Act, or "AIA," made significant changes to the patent system, including:
First-Inventor-to-File Priority System. The AIA shifted the U.S. patent priority rule from a "first-to-invent" system to the "first-inventor-to-file principle" while allowing for a one-year grace period. Prior User Rights. The legislation established an infringement defense based upon an accused infringer's prior commercial use of an invention patented by another. Assignee Filing. Under the AIA, a patent application may be filed by the inventor's employer or other entity to which rights in the invention are assigned. Post-Grant Review Proceedings. The AIA changed the current system of administrative patent challenges at the U.S. Patent and Trademark Office (USPTO) by establishing post-grant review, inter partes review, and a transitional program for business method patents. Public Participation in USPTO Procedures. The legislation allowed members of the public to submit pertinent information to the USPTO concerning particular applications both before and after patent issuance. USPTO Fees. The AIA stipulated fees for USPTO patent services and allows the agency to adjust the fees in order to cover its costs. It also required that fees collected above the amount provided for in the appropriations process be used only for the USPTO. Patent Marking. The AIA limited lawsuits challenging patent owners with false patent marking and allowed for virtual, Internet-based marking. Patentable Subject Matter. The AIA prevented patents claiming or encompassing human organisms and limited the availability of patents claiming tax strategies. Best Mode. The statute maintained the requirement that patents describe the best mode, or superior way for practicing the claimed invention, but eliminated failures to do so as a basis for invalidating the patent.
The AIA introduced a number of additional changes to the patent law, including changes to the venue and joinder statutes, the introduction of supplemental examination, and a clarification of the law of willful infringement.
Although the AIA arguably made the most significant changes to the U.S. patent statute since the 19th century, the legislation did not reflect all of the issues that were the subject of congressional discussion including the assessment of damages during infringement litigation and the publication of all pending patent applications prior to grant.