Navigating the Post‑Kroy PTAB Landscape: Strategic Guidelines for Patent Owners

The Federal Circuit’s Feb. 10, 2025 decision in Kroy IP Holdings, LLC v. Groupon, Inc. fundamentally shifts the interplay between district‑court patent litigation and Patent Trial and Appeal Board (PTAB) inter partes reviews (IPRs). In holding that a PTAB final written decision invalidating certain claims cannot collaterally estop a patentee from later asserting immaterially different claims in district court, the Federal Circuit recalibrated longstanding assumptions about estoppel, burdens of proof and claim‑assertion strategy.

Patent owners should now reassess how they structure infringement complaints, manage claim portfolios and engage in parallel PTAB proceedings. Below are practical guidelines to help patent holders maximize leverage, minimize risk and navigate the evolving patent‑litigation landscape.

Key Takeaways from Kroy

• No PTAB‑to‑District‑Court Estoppel for Unchallenged Claims. Because IPRs apply a preponderance‑of‑the‑evidence standard and district courts require clear and convincing proof of invalidity, a PTAB finding of unpatentability does not bar assertion of unadjudicated claims—even if immaterially different—from the same patent.
• XY and Ohio Willow Wood Remain Limited. Kroy distinguishes prior collateral‑estoppel precedents (XY, Ohio Willow Wood) as applying only when the same claim was finally cancelled, or when two district‑court actions share identical burdens and issues.
• Strategic “Hold‑Back” of Claims. Patent owners can—and likely should—consider withholding strongest fallback claims from an initial complaint, preserving them for post‑IPR assertion if initially asserted claims fall.

Recommendations for Patent Assertion Strategy

1. Tier Your Claim Portfolio

- Primary Claims (Tier 1): Assert your broadest, strongest claims first. These set infringement themes, attract early discovery, and anchor damages demands.

- Fallback Claims (Tier 2): Reserve immaterially different claims that recite similar inventive concepts but avoid PTAB challenges until necessary.

Why: Kroy permits later assertion of Tier 2 claims without fear of PTAB estoppel.

2. Draft Complaints with Intentional Gaps

- File an initial complaint asserting a subset of your strongest claims.

- Incorporate a reservation-of-rights clause stating that you may amend to add other claims.

- Align amendment timing with PTAB final decisions (e.g., immediately post‑IPR).

Why: This staged approach preserves district‑court venue and leverage if PTAB invalidates Tier 1 claims.

3. Monitor District‑Court Scheduling Orders

- Confirm deadlines for claim identification, amendment, and expert disclosures.

- Use Rule 15 to amend within scheduling windows, avoiding “trial by ambush” objections.

PTAB Practice Considerations

4. Selective PTAB Defense

- Defensive IPRs: If you are sued, consider challenging only Tier 1 claims initially asserted.

- Offensive IPRs: When petitioning against competitor patents, ensure all plausible claims—including immaterial variants—are challenged. Filing multiple petitions may be costly but mitigates later district‑court exposure.

Why: Failing to challenge immaterially different claims at PTAB leaves them intact for district‑court assertion.

5. Leverage PTAB Findings

- Use PTAB invalidation of Tier 1 claims as leverage in settlement negotiations, while reserving Tier 2 claims as “nuclear” fallback.

District‑Court Litigation Tactics

6. Anticipate Amendments

- Opposing party motions to dismiss on estoppel grounds should be met with Kroy’s holding: different burdens of proof bar estoppel.

- Prepare expert opinions in parallel to anticipate invalidity challenges under the clear‑and‑convincing standard.

7. Stay vs. Proceed

- Consider (if other circumstances support) seeking district court stays pending PTAB resolution when asserting Tier 1 claims—but preserve Tier 2 claims for later assertion if needed.

- Keep in mind that because the Fintiv doctrine looks to be alive and well, the ideal situation is to get IPRs not instituted due to efficiency of retrying validity issues that the district court will likely adjudicate first. But if the IPR is instituted, the above stay strategy may make sense.

Portfolio Management & Drafting Best Practices

8. Claim Differentiation

- Draft dependent claims with immaterial differences (e.g., alternative parameters, functional language) to serve as Tier 2 fallbacks.

- Maintain a clear specification basis to facilitate amendment without new matter issues.

9. Maintain Clear File Histories

- Document prosecution rationales distinguishing each claim group to preempt indefiniteness or written‑description attacks.

Risk Mitigation Checklist

Conclusion

Kroy v. Groupon empowers patent owners to adopt a staggered claim‑assertion strategy that preserves leverage across parallel PTAB and district‑court proceedings. By intentionally selecting which claims to assert, monitoring procedural deadlines, and differentiating claim scope, patent holders can maximize enforcement value while minimizing exposure to estoppel.

While the decision increases tactical complexity, it also reinforces the fundamental property right in patents: claims not finally invalidated remain presumptively valid until proven otherwise under the highest evidentiary standard. Patent owners who integrate these guidelines into litigation playbooks will be well positioned to navigate—and thrive in—the post‑Kroy era.