Patent Reexamination Enhancement Act of 2001

Patent Reexamination Enhancement Act of 2001 - Amends Federal patent law to allow any person, within 12 months after issuance of a patent, to file a request for an inter partes reexamination by the Patent and Trademark Office (PTO): (1) on the basis of evidence that the invention was known or used by others in this country, or patented or described in a printed publication in this or a foreign country, before the invention by the applicant for patent; (2) that the invention was patented or described in a printed publication in this or a foreign country or in public use or on sale in this country, more than one year before the application for U.S. patent; (3) on the basis of (1) or (2) alone or in combination with a prior art citation to the PTO consisting of patents or printed publications which that person believes to have a bearing on the patentability of any claim of a particular patent; or (4) on the basis of evidence showing that one or more claims of the patent do not comply with certain patent application specification requirements (other than the best mode requirement).

Requires such request to set forth reasons demonstrating a substantial new question of patentability exists in light of certain required conditions for patentability for each claim of the patent for which reexamination is requested.

Sets a 12-month deadline for the PTO Director to determine whether a substantial new question of patentability affecting a claim is raised, on the grounds specified in this Act.

Revises the estoppel of a third-party requester whose request for an inter partes reexamination results in a final decision favorable to the patentability of any original or proposed amended or new claim of the patent.

Allows the assertion of invalidity based on newly discovered information unavailable to the third-party requester and the PTO, or upon evidence and reasons set forth in this Act which were not known to the third party requester at the time of such proceedings.

Amends the Intellectual Property and Communications Omnibus Reform Act of 1999 to repeal the estoppel effect of an inter partes reexamination.