A client has just been sued by a U.S. domestic manufacturer of a patented hypodermic needle. After reviewing the patent claims and prior art, you determine the patent may be invalid. Which forum(s) may be suitable for challenging the patent?

There are several forums where a patent can be challenged in the United States:

1. Inter Partes Review (IPR): This is a trial proceeding conducted at the Patent Trial and Appeal Board (PTAB) to review the patentability of one or more claims in a patent only on a ground that could be raised under sections 102 or 103, and only on the basis of prior art consisting of patents or printed publications.

2. Post-Grant Review (PGR): This is another trial proceeding conducted at the PTAB where the patentability of one or more claims in a patent can be reviewed on any ground that could be raised under paragraph (2) or (3) of section 282(b) (relating to invalidity of the patent or any claim). PGR proceedings must be initiated within 9 months of the grant of the patent or of the issuance of a reissue patent.

3. Ex Parte Reexamination: This is a proceeding conducted by the USPTO where the patentability of one or more claims in a patent is reexamined. The request for reexamination can be filed by any person at any time during the period of enforceability of a patent.

4. Federal Court: A patent can also be challenged in federal court, either in a declaratory judgment action brought by a party threatened with infringement, or as a defense in an infringement suit brought by the patent owner.

5. The United States International Trade Commission (ITC): If the patent owner has filed a complaint alleging infringement by imported goods,