The PTAB: inter partes review, post-grant review and appeals

The Patent Trial and Appeal Board hears appeals from examiners’ rejections and conducts the trials the America Invents Act created: inter partes review and post-grant review. Whether a petition is instituted, and whether the Director reviews a decision, now shapes much of patent litigation.

Start with the comparisons of the three ways to challenge a patent, then follow the Board’s precedential decisions, Director Review and guidance below, and see institution rates on our dashboard.

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  1. 1IPR vs. PGR: Inter Partes Review and Post-Grant Review ComparedIPR vs. PGR: who may file and when, the grounds each allows, institution standards, fees, timelines, estoppel, and how the Director now decides institution.
  2. 2IPR vs. Ex Parte Reexamination: How the Two Patent Challenges DifferIPR vs. ex parte reexamination: who may file and when, the thresholds, cost, timing, anonymity, amendments, appeal rights and estoppel, current to 2026.
  3. 3PTAB vs. District Court: Where to Challenge a Patent’s ValidityPTAB vs. district court for patent invalidity: standard of proof, grounds, timing, cost, estoppel, discretionary denial and appeal, as of 2026.

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General information, not legal advice. How we write and check these guides: our editorial policy.