For an accused infringer, a Patent Office challenge can provide a separate route to contest patent claims. Choosing that route requires more than finding a relevant patent or publication. Counsel should compare the available procedures with the defenses and schedule in court.
Which procedure fits the grounds?
IPR is limited by 35 U.S.C. 311(b) to anticipation and obviousness based on patents or printed publications. PGR permits broader statutory invalidity grounds for eligible patents, generally within nine months after grant or reissue. Ex parte reexamination is an examination procedure based on qualifying prior art, with more limited third-party participation.
What can prevent institution?
Check the service-based filing bar and earlier validity-action restrictions in section 315. Then assess the statutory institution threshold and discretionary considerations. Under the October 17, 2025 USPTO memorandum, the Director decides institution after consultation with PTAB judges. The March 11, 2026 memorandum adds specified manufacturing and small-business considerations. A strong merits argument alone does not ensure a trial.
Will filing pause an infringement lawsuit?
Do not budget on that assumption. A stay of an existing infringement action generally depends on the court's discretion, including potential simplification, litigation progress, and prejudice. The separate statutory rules for a petitioner's later-filed validity action and certain parallel ITC proceedings require their own analysis.
What estoppel should I consider?
IPR estoppel under section 315(e) follows a final written decision concerning a claim. It is not limited to cases where the petitioner loses. The restriction covers grounds raised or reasonably available in the IPR and extends to specified related parties. PGR has a separate estoppel provision in section 325(e). Review the effect on defenses in other forums before filing.
How should I make the decision?
Ask counsel to compare the proposed grounds, timing, participation, institution risk, parallel proceedings, and total cost. Identify which issues the Office could resolve and which would remain in court. The linked IPR, reexamination, and stay guides explain those questions in more detail.