In a closely watched patent dispute filed in the Central District of California, the court granted Amazon.com, Inc.’s motion to stay proceedings in Longitude Licensing Limited v. Amazon.com, Inc. (Case No. 8:23-cv-00039), halting the infringement action pending resolution of three inter partes review (IPR) proceedings: IPR2023-01200, IPR2023-01230, and IPR2023-01286. The case, which involves four patents covering output buffer circuits, semiconductor devices, supply voltage generating circuits, and memory-controller systems, was administratively closed on February 26, 2024, just over 13 months after being filed.

The stay ruling carries significant strategic weight for patent holders asserting semiconductor and integrated circuit patents against major technology companies. As IPR proceedings increasingly serve as a first line of defense for well-resourced defendants, the outcome of these PTAB reviews will determine whether this litigation resumes — and on what terms. IP professionals, patent litigators, and R&D teams operating in the memory and semiconductor design space should monitor the IPR outcomes closely, as the final written decisions will dictate the future landscape of these asserted claims.

Case Overview

The Parties

The Patents at Issue

The four patents at issue cover foundational semiconductor circuit technologies. U.S. Patent No. RE43,539 relates to output buffer circuits used in integrated semiconductor devices to manage signal transmission between components. U.S. Patent Nos. 9,207,701 and 9,379,233 cover semiconductor device architectures and supply voltage generation circuits that regulate power delivery within chips. U.S. Patent No. 7,697,369 is directed at systems integrating a controller and memory, a configuration central to modern computing and cloud infrastructure hardware.

• • USRE043539E
• • US9207701B2
• • US9379233B2
• • US7697369B2

Legal Representation

Plaintiff Counsel: Russ August & Kabat LLP (lead: Brian D. Ledahl)
Defendant Counsel: Haynes & Boone LLP; Perkins Coie LLP (lead: Andrea Levenson)

Litigation Timeline & Procedural History

The case was filed on January 9, 2023, in the Central District of California — a jurisdiction that, while not the Eastern District of Texas, remains a viable venue for patent plaintiffs given its established IP docket and proximity to major technology defendants operating on the West Coast. As a first-instance district court proceeding, the case was subject to standard Markman claim construction briefing, with a hearing scheduled for April 4, 2024, before the stay was entered.

The litigation lasted 413 days before being administratively closed — a duration that reflects the time required for Amazon to mount and initiate IPR proceedings at the Patent Trial and Appeal Board before moving for a stay in district court. The case was resolved not by trial, jury verdict, or settlement, but by a court-ordered stay pending PTAB final written decisions in three parallel IPR proceedings. Notably, the Markman hearing was vacated as part of the stay order, meaning no claim construction rulings have yet issued, preserving significant legal uncertainty around the scope of the asserted claims.

The Verdict & Legal Analysis

Outcome

The Central District of California granted defendant Amazon’s motion to stay all proceedings in Case No. 8:23-cv-00039 pending the resolution of IPR2023-01200, IPR2023-01230, and IPR2023-01286 before the Patent Trial and Appeal Board. No damages were awarded, no injunctive relief was granted, and no claim construction determinations were made, as the Markman hearing was vacated. The case was administratively closed on February 26, 2024, with parties directed to file a joint status report within 10 days of any final written IPR decisions.

Verdict Cause Analysis

The court’s stay determination turned on the traditional three-factor balancing test applied in patent cases involving parallel PTAB proceedings

• The court found that the stage of litigation favored a stay, as claim construction had not yet occurred and no substantive merits rulings had issued, minimizing waste of judicial resources.
• Amazon’s initiation of three separate IPR proceedings against the four asserted patents was found to present a meaningful likelihood of simplifying the issues for trial, satisfying the second stay factor.
• The court determined that Longitude Licensing would not suffer undue prejudice from the stay, a finding consistent with courts’ treatment of non-practicing entities that primarily seek monetary damages rather than injunctive relief.
• On balance, all three traditional stay factors — stage of litigation, simplification of issues, and prejudice to the non-moving party — weighed in favor of granting the stay, consistent with the strong federal policy favoring PTAB review.

Legal Significance

1. 1. This ruling reinforces the well-established principle that district courts will liberally grant stays pending IPR when proceedings are instituted before claim construction, effectively resetting the litigation clock in favor of defendants who act early with PTAB petitions.
2. 2. The vacatur of the Markman hearing means that claim scope for all four asserted patents — including reissue patent RE43,539 — remains entirely open, and PTAB’s analysis of claim validity may shape how surviving claims are later construed in district court.
3. 3. The outcome of the three IPR proceedings will have direct implications for any other licensees or defendants facing assertions from Longitude Licensing on the same semiconductor patent portfolio, making the PTAB final written decisions of broad interest beyond this case.

Strategic Takeaways

For Patent Attorneys:

• File IPR petitions as early as possible after service of a complaint — Amazon’s ability to initiate three IPRs and obtain a stay before Markman demonstrates the strategic value of rapid PTAB engagement.
• When representing patent assertion entities against well-resourced defendants, proactively address the undue prejudice prong in your stay opposition briefing, particularly by arguing that monetary remedies are inadequate or that market harm is ongoing.
• Monitor the PTAB docket for IPR2023-01200, IPR2023-01230, and IPR2023-01286, as final written decisions will determine whether the district court litigation resumes and which claims survive for assertion.
• In cases involving reissue patents such as RE43,539, consider whether reissue prosecution history creates additional claim construction arguments or intervening rights defenses that can be leveraged independently of IPR outcomes.

For IP Professionals:

• Track the three pending IPR proceedings as leading indicators of claim viability across Longitude Licensing’s semiconductor portfolio — any cancellation or amendment of claims will directly affect licensing exposure for similarly situated companies.
• Audit your own semiconductor product lines against the four asserted patents now, during the stay, to prepare design-around analyses or claim differentiation arguments before litigation potentially resumes.

For R&D Teams:

• Teams developing output buffer circuits, supply voltage regulators, or memory-controller integrated systems should use the IPR stay period as an opportunity to conduct FTO assessments against the asserted patent families before district court proceedings resume.
• The involvement of USRE043539E — a reissued patent — signals that the original patent claims were broadened or corrected post-grant; R&D teams should evaluate whether their designs fall within the original or reissued claim scope when assessing infringement risk.