On February 3, 2026, the United States Patent and Trademark Office (USPTO) de-designated Proppant Express Investments, LLC v. Oren Technologies, LLC and Adello Biologics LLC v. Amgen Inc. from precedential status. In both decisions, the Patent Trial and Appeal Board (PTAB) held that a petitioner may amend its identification of real parties in interest (RPIs) while maintaining the petition’s original filing date after considering: (1) whether the petitioner has attempted to circumvent the time bar or estoppel rules; (2) petitioner bad faith; (3) prejudice to a patent owner from the delay; and (4) petitioner gamesmanship. Proppant Express Invests., LLC v. Oren Techs., LLC, IPR2017-01917, Paper 86 (PTAB Feb. 13, 2019); Adello Biologics LLC v. Amgen Inc., PGR2019-00001, Paper 11 (PTAB Feb. 14, 2019).
These decisions are de-designated and no longer binding on the PTAB because they conflict with the decision in Corning Optical Communications RF, LLC v. PPC Broadband Inc., IPR2014-00440, Paper 68 (PTAB Aug. 18, 2015) (precedential) (“Corning Optical“), which holds that a petitioner’s amended identification of RPIs requires according the petition a new filing date. Corning Optical, IPR2014-00440, Paper 68 at 23.
The Corning Optical Rule: No Second Chances on RPI Disclosure
The reinstated Corning Optical decision establishes a bright-line rule with severe consequences for petitioners who fail to properly identify all real parties in interest at the outset of inter partes review proceedings.
In Corning Optical, the PTAB granted Patent Owner PPC Broadband’s motion to dismiss three IPR proceedings and vacated its earlier institution decisions after determining that Petitioner Corning Optical Communications RF, LLC failed to identify two related Corning entities as RPIs: its parent company Corning Incorporated and its sister company Corning Optical Communications LLC (Corning NC). The Board’s analysis focused on two critical inquiries: funding and control.
The evidence revealed:
Corning Inc.’s involvement:
- Hired outside counsel through an engagement letter signed by a Corning Inc. executive
- Paid all invoices for the IPR proceedings through its payment system
- Its IP Department attorneys directed counsel and participated in settlement discussions
- Acted as the “in-house Case Manager” per the engagement letter
Corning NC’s entanglement:
- Shared the same President, Secretary, and other officers with Petitioner
- Officers held identical titles at both entities and managed the same product lines
- Corporate boundaries were “so intertwined that it is difficult for both insiders and outsiders to determine precisely where one ends and another begins”
- Marketing and selling the accused products while Petitioner manufactured them
The Unforgiving Consequence
The Board held that under 35 U.S.C. § 312(a)(2), an IPR petition may be considered “only if” it identifies “all” real parties in interest. Because this statutory requirement was not met, the petitions were deemed incomplete and could not be considered. Critically, the Board ruled that any corrected petition identifying the additional RPIs would receive a new filing date under 37 C.F.R. § 42.106(b). Since Patent Owner had sued Petitioner more than a year before any possible new filing date, the corrected petitions would be time-barred under 35 U.S.C. § 315(b)’s one-year limitation.
Result: Complete dismissal without any merits determination on patent validity. The Corning Optical panel explicitly rejected arguments that petitioners should be allowed to correct RPI disclosures without losing their filing date—the exact approach later adopted in Proppant Express and Adello Biologics.
Implications for Practitioners
With the de-designation of Proppant Express and Adello Biologics, the USPTO has restored Corning Optical‘s uncompromising standard. Practitioners must understand:
1. No room for error. RPI disclosure is not subject to the PTAB’s typical flexibility on procedural matters. Get it wrong at filing, and there’s no do-over.
2.Investigate thoroughly before filing. Corporate structures involving parents, subsidiaries, and sister companies require careful analysis. Consider:
- Who is funding the proceeding?
- Who hired and directs counsel?
- Who controls litigation strategy and settlement discussions?
- Are corporate boundaries sufficiently distinct, or do shared officers and intertwined operations blur the lines?
3. The one-year bar becomes a trap. Combined with § 315(b)’s time limitation, an RPI disclosure error can be fatal if discovered after the one-year window closes.
4. Patent owners have leverage. Strategic patent owners can use RPI challenges as a procedural kill shot, obtaining dismissal without ever addressing patent validity.
5. Over-disclosure is safer than under-disclosure. When in doubt, name additional entities as RPIs. The consequences of omission far outweigh any perceived strategic advantage of limiting disclosure.
The USPTO’s decision to de-designate Proppant Express and Adello Biologics signals a return to strict enforcement of statutory requirements. The four-factor balancing test adopted in those decisions—considering circumvention, bad faith, prejudice, and gamesmanship—introduced discretion that the agency apparently concluded was inconsistent with the mandatory language of § 312(a)(2). By restoring Corning Optical as controlling precedent, the USPTO has chosen clarity and predictability over flexibility. Petitioners now have clear notice: identify all RPIs correctly at filing, or risk losing everything on a technicality.
The authors of www.PatentLawyerBlog.com are patent trial lawyers at Jeffer Mangels & Mitchell LLP. For more information about this case, contact Greg Cordrey at 949.623.7236 or GCordrey@jmbm.com.