Answer ... A patent’s validity can be challenged in post-grant proceedings before the US Patent and Trademark Office (USPTO) or in district court.

The USPTO provides three mechanisms to challenge the validity of an issued patent and petition for its review:

• ex parte re-examinations;
• inter partes review (IPR); and
• post-grant review (PGR) (35 USC §§ 301 et seq).

In addition to these USPTO proceedings, validity may be challenged in district court affirmatively as a declaratory judgment action or as a defence to a claim of infringement (35 USC § 282(b); 28 USC § 2201). A party may also raise an invalidity defence at the US International Trade Commission (ITC).

Answer ... As mentioned in question 4.1, the USPTO provides three post-grant proceedings for a party to challenge the validity of an issued patent:

• An ex parte re-examination petition may be filed at any time during a patent’s enforcement period (35 USC § 302). The petitioner, which has the option of remaining anonymous, asserts patents or printed publications that raise “a substantial new question of patentability” (35 USC §§ 301, 303). Unlike in IPRs and PGRs, however, the petitioner is not involved in re-examination, which is between only the patentee and the USPTO.
• A petition for IPR is limited to anticipation and obviousness challenges under 35 USC §§ 102 and 103, and the petitioner may only assert patents or printed publications as prior art references (35 USC § 311(b)). The Patent Trial and Appeal Board (PTAB) will institute this proceeding if there is a “reasonable likelihood” that one of the challenged claims is unpatentable (35 USC § 314(a)).
• A petition for PGR can raise any ground for patent invalidity, except failure to comply with the best mode requirement (35 USC § 321(b)). The PTAB will institute this proceeding if it is “more likely than not” that one of the challenged claims is unpatentable (35 USC § 324(a)).

In addition to these USPTO proceedings, validity may be challenged in district court affirmatively as a declaratory judgment action or as a defence to a claim of infringement (35 USC § 282(b)). A party may also raise an invalidity defence at the ITC.

Answer ... In district court, at the ITC and in PGRs before the PTAB, a patent’s validity can be challenged on any ground except a failure to satisfy the best mode requirement (35 USC §§ 282(b), 321(b)). That is, a patent can be challenged as to novelty, obviousness, statutory subject matter, written description, enablement or definiteness (id).

In ex parte re-examinations and IPRs, a patent’s validity can be challenged only on novelty and obviousness grounds, and the asserted prior art references are limited to patents and printed publications (35 USC §§ 301(a), 311(b)).

Answer ... The evidentiary standard to challenge an issued patent depends on the forum. In district court, patents are presumed valid and a challenger must prove invalidity by clear and convincing evidence (35 USC § 282; Microsoft Corp v i4i Ltd, 564 US 91, 95 (2011)). In contrast, in any post-grant proceeding before the USPTO, there is no presumption of validity and the challenger must establish unpatentability by the lesser preponderance of the evidence standard (Cuozzo Speed Techs, LLC v Lee, 136 S Ct 2131, 2144 (2016); 35 USC § 316(e); 35 USC § 326(e)).

Answer ... Third parties may challenge the validity of an issued patent before the USPTO through any of the three post-grant proceedings – ex parte re-examination, IPR and PGR.

In a PGR, a petitioner can raise any ground of invalidity available under 35 USC § 282(b), including novelty, obviousness, statutory subject matter, written description, enablement or definiteness (35 USC § 321(b)). In an IPR or ex parte re-examination, the petitioner’s invalidity challenges are limited to novelty and obviousness based on patents or printed publications (35 USC §§ 301(a), 311(b)).

Answer ... Under the America Invents Act, “any person” may file a petition for ex parte re-examination (35 USC § 302), and “a person who is not the owner of [the] patent” may file a petition for an IPR or a PGR (35 USC §§ 311(a), 321(a)).

Answer ... The timing to request review varies with the type of proceeding. While requests for re-examination may be filed “at any time” (35 USC § 302), petitions for PGRs and IPRs have strict timing requirements. Petitions for PGRs must be filed “not later than the date that is 9 months after the date of the grant of the patent or of the issuance of a reissue patent (as the case may be)” (35 USC § 321(c)). A petition for an IPR can be filed only at the later of nine months after the patent’s issuance or termination of any PGR (35 USC § 311(c)).

Importantly, IPRs and PGRs cannot be instituted if the petitioner filed a civil action challenging the patent’s validity prior to filing its petitions (35 USC §§ 315(a)(1), 325(a)(1)). A counterclaim for invalidity, notably, does not qualify as a civil action challenging validity (35 USC §§ 315(a)(3), 325(a)(3)). A petition for an IPR is additionally time barred if the petitioner was served with a complaint for infringement of the patent more than one year prior to the date the petition was filed (35 USC § 315(b)).

Answer ... As with district court litigation, PGRs may raise any ground of unpatentability available under 35 USC § 282(b), including novelty, obviousness, statutory subject matter, written description, enablement or definiteness (35 USC § 321(b)). As set forth in § 282(b), an alleged failure to satisfy the best mode requirement is not available as an asserted ground of invalidity.

IPRs and ex parte re-examinations are more limited. Under these proceedings, a patent’s validity may be challenged only as to novelty and obviousness, and only patents and printed publications may serve as asserted prior art references (35 USC §§ 301(a), 311(b)).

Answer ... Upon the filing of any petition for post-grant examination, the USPTO will first determine whether to conduct the requested review. Ex parte re-examinations will be instituted if a “substantial new question of patentability” is presented (35 USC § 303). Institution of IPRs requires there to be a “reasonable likelihood” that the petitioner would prevail in establishing that at least one challenged claim is unpatentable (35 USC § 314(a)). For institution of a PGR, it must be “more likely than not” that at least one challenged claim will be found unpatentable (35 USC § 324(a)). If the petition does not meet the applicable standard, then the requested re-examination will not be instituted and the challenged patent will remain in effect.

If a post-grant examination of an issued patent is instituted, the claims could be:

• determined unpatentable and cancelled;
• confirmed; or
• amended and determined patentable (35 USC §§ 307, 318, 328).

Answer ... In district court and the ITC, patents are presumed valid and a challenger must prove invalidity by clear and convincing evidence (35 USC § 282; Microsoft Corp v i4i Ltd, 564 US 91, 95 (2011)). If the challenger does not meet this burden, the court will not find the patent valid – just that the challenger “did not carry the burden of establishing invalidity in the particular case before the court” (In re Baxter Int’l, Inc, 678 F3d 1357, 1364 (Fed Cir 2012) (quotations and alterations omitted)).

In contrast, in any post-grant proceeding before the USPTO, there is no presumption of validity and the challenger must establish unpatentability by the lesser preponderance of the evidence standard (Cuozzo Speed Techs, LLC v Lee, 136 S Ct 2131, 2144 (2016); 35 USC § 316(e); 35 USC § 326(e)).

Answer ... The decision on whether to institute USPTO re-examination proceedings, including IPRs and PGRs, is not appealable (35 USC §§ 303(c), 314(d), 324(e)).

If, however, the PTAB institutes an IPR or PGR, “any party” to that proceeding “dissatisfied with the final written decision of the [PTAB] … shall have the right to be a party to the appeal” to the Federal Circuit (35 USC §§ 319, 329). Importantly, the party seeking Federal Circuit review must meet the constitutional standing requirements of Article III to pursue an appeal (Phigenix, Inc v Immunogen, Inc., 845 F3d 1168 (Fed Cir 2017)). That is, the appealing party must have suffered some actual or threatened injury, which is fairly traceable to the non-appealing party and can be redressed by a favourable decision (Lujan v Defs of Wildlife, 504 US 555, 560-61 (1992)). This means that while any third party may file a petition for an IPR or PGR, only those that satisfy Article III standing may appeal an unfavourable PTAB decision to the Federal Circuit.

Ex parte re-examinations, on the other hand, are first decided by the USPTO’s Central Re-examination Unit and can be appealed to the PTAB. A patent owner may then appeal the PTAB’s decision to the Federal Circuit (35 USC § 306).