Klein Tools Inc. v. Milwaukee Electric Tool Corp.

Klein Tools Inc. and Milwaukee Electric Tool Corp. are both well-established American operating companies in the tool manufacturing industry, primarily serving professional tradespeople. Klein Tools, founded in 1857, specializes in hand tools, particularly for the electrical and telecommunications industries, and has expanded its product line to include a wide range of hand tools, occupational protective equipment, and limited power tools. Milwaukee Electric Tool Corp., established in 1924, is a multinational company known for developing, manufacturing, and marketing heavy-duty power tools, hand tools, tool accessories, and storage solutions, with a strong emphasis on innovation in cordless systems and battery technology.

This case, IPR2026-00246, involves Klein Tools Inc. challenging US Patent No. 11,857,064, owned by Milwaukee Electric Tool Corp., before the Patent Trial and Appeal Board (PTAB). While the specific claims challenged in this IPR require reviewing the petition, this IPR is linked to an underlying patent infringement lawsuit, Milwaukee Electric Tools Corporation v. Klein Tools, Inc., Case No. 1:25-cv-04689, filed in the U.S. District Court for the Northern District of Illinois. In that district court litigation, Milwaukee Tool asserted patents, including the '064 patent, against Klein Tools' MODbox™ modular tool storage system, alleging infringement of features related to stacking, locking, and coupling. The '064 patent itself is titled "MODULAR TOOLBOX SYSTEM" and describes aspects of such systems.

The procedural posture of this case is an Inter Partes Review (IPR) before the Patent Trial and Appeal Board (PTAB), a specialized administrative court within the USPTO. The PTAB provides an alternative forum to district courts for challenging patent validity. This IPR is part of a larger, ongoing intellectual property dispute between these two industry competitors concerning modular tool storage systems. Notably, there were previous IPRs (IPR2024-01400, IPR2024-01401) between these parties that involved discussions around discretionary denial under the Fintiv factors, particularly in the context of parallel International Trade Commission (ITC) investigations and district court litigation, indicating a strategic and complex battle over their respective modular storage technologies. The dispute highlights the intense competition and significant investment in the modular jobsite storage market, making the case notable for its potential impact on design and innovation within the professional tool industry.

Parallel IPR Proceeding and Related District Court Litigation Underway for Klein Tools v. Milwaukee Electric Tool

Washington, D.C. - A patent dispute between tool manufacturing giants Klein Tools Inc. and Milwaukee Electric Tool Corp. is unfolding across both the Patent Trial and Appeal Board (PTAB) and the U.S. District Court for the Northern District of Illinois. Klein Tools Inc. initiated an Inter Partes Review (IPR) against Milwaukee Electric Tool Corp., challenging US Patent 11857064, while a related district court patent infringement case is navigating jurisdictional challenges.

Key Legal Developments:

IPR2026-00246 (PTAB)

• Filing of IPR Petition (2026-01-30): Klein Tools Inc. filed an IPR petition, IPR2026-00246, with the Patent Trial and Appeal Board, challenging the validity of US Patent 11857064, owned by Milwaukee Electric Tool Corp. The case is currently pending.
• Request to File Reply (2026-05-20): Klein Tools requested leave to file a five-page reply to Milwaukee's Preliminary Response. This reply aims to address Milwaukee's arguments for discretionary denial, which are based on alleged inconsistent claim-construction and indefiniteness positions taken by Klein Tools across different forums, including a district court proceeding that Milwaukee moved to dismiss.

District Court Litigation: Milwaukee Electric Tool Corp. v. Klein Tools Inc., Case No. 1:25-cv-04689 (N.D. Ill.)

• Complaint Filed (2025-04-29): Milwaukee Electric Tool Corp. filed a patent infringement lawsuit against Klein Tools Inc. in the U.S. District Court for the Northern District of Illinois. The complaint alleged that several Klein tape measures infringed upon Milwaukee's patent-protected features, specifically citing a patent granted in May 2023 covering a "tape blade profile increasing tape standout." The lawsuit sought a permanent injunction and financial damages, including the possibility of triple damages for willful infringement. This case directly involves patent '064.
• Discovery of Lack of Standing (Mid-January 2026): Milwaukee Tool determined in mid-January 2026 that it lacked constitutional standing at the time of filing the complaint. This realization stemmed from agreements between Milwaukee Tool and another entity that affected the ownership of the asserted patents, including '064 and '067.
• Notification and Intent to Dismiss (2026-02-13 - 2026-03-10): Milwaukee Tool notified Klein Tools of the standing issue on February 13, 2026, and produced the relevant agreements. Milwaukee stated its intention to file a motion to dismiss the case without prejudice and refile it once constitutional standing was corrected. Although Klein Tools agreed that Milwaukee lacked standing at the time of filing, it indicated an intent to oppose Milwaukee's motion to dismiss. The parties met on March 3, 2026, to discuss the proposed dismissal and the potential use of discovery in any new litigation.

Related but Separate Litigation:

It is important to distinguish these proceedings from another patent infringement case filed by Milwaukee Electric Tool Corporation and Keter Home and Garden Products Ltd. against Klein Tools, Inc. (Case No. 1:24-cv-04284, N.D. Ill.), which was filed on May 23, 2024, and voluntarily dismissed without prejudice on July 22, 2024. This earlier case focused on three different U.S. patents related to modular toolbox and storage system technology, specifically Milwaukee's PACKOUT™ system and Klein's MODbox™ product line, and concluded before Klein Tools filed an answer. Another case, 1:24-cv-04928, also filed in June 2024, also appears to relate to MODbox patents, but its specific connection to the other cases or status is less clear from the available information. Furthermore, IPR2024-01400 and IPR2024-01401, also between these parties, saw institution denied on Director Review on June 9, 2025, based on Fintiv factors related to parallel ITC investigations, but these IPRs did not involve patent 11857064.

The current focus remains on IPR2026-00246 and the related district court case 1:25-cv-04689, which directly concerns US Patent 11857064 and is currently grappling with jurisdictional issues related to standing.

Klein Tools Inc., the petitioner in IPR2026-00246, is represented by attorneys from Kirkland & Ellis LLP.

The identified counsel are:

• W. Todd Baker

  • Role: Partner (likely lead counsel for PTAB proceedings)
  • Firm: Kirkland & Ellis LLP, Washington, D.C. office.
  • Experience Note: Mr. Baker is an IP litigation partner with over 25 years of experience, focusing on post-grant matters at the USPTO, including Inter Partes Review (IPR) and Post Grant Review (PGR) proceedings before the Patent Trial and Appeal Board. He has successfully represented Klein Tools, Inc. in previous PTAB proceedings, securing discretionary denial of institution for three petitions related to Milwaukee Electric Tool Corporation. He is also recognized in The Best Lawyers in America® 2026 for Patent Law.

• Ryan Kane

  • Role: Trial Lawyer / Attorney (appears pro hac vice)
  • Firm: Kirkland & Ellis LLP, New York, New York office.
  • Experience Note: Mr. Kane is a trial lawyer with significant experience in complex commercial and intellectual property disputes, including first-chairing high-stakes matters in federal court, arbitration, and at the U.S. International Trade Commission. He has defended clients in patent infringement suits and inter partes review proceedings, successfully invalidating key patent claims at the USPTO and obtaining favorable verdicts or settlements. He has legal familiarity with U.S. Patent No. 11,857,064 due to underlying litigation. He is a member of the New York Bar.

Milwaukee Electric Tool Corp. (Milwaukee Tool) is represented by attorneys from Morgan, Lewis & Bockius LLP and Kirkland & Ellis LLP in the related district court litigation, Milwaukee Electric Tools Corporation v. Klein Tools, Inc., Case No. 1:25-cv-04689.

The following counsel represent Milwaukee Electric Tool Corp. in the related district court case and are likely involved in the IPR:

From Morgan, Lewis & Bockius LLP:

• Scott D. Sherwin (Lead Counsel) - Partner at Morgan, Lewis & Bockius LLP. He was involved in previous IPR challenges for Milwaukee Tool regarding lithium-ion battery patents.
• Jason C. White (Lead Counsel) - Partner at Morgan, Lewis & Bockius LLP. He also worked on the previous IPR challenges for Milwaukee Tool concerning lithium-ion battery patents.
• Karon N. Fowler (Counsel) - Attorney at Morgan, Lewis & Bockius LLP.
• Dion M. Bregman (Counsel) - Attorney at Morgan, Lewis & Bockius LLP.
• Maria E. Doukas (Counsel) - Attorney at Morgan, Lewis & Bockius LLP.
• Michael Barboun (Counsel) - Attorney at Morgan, Lewis & Bockius LLP.

From Kirkland & Ellis LLP:

• Brian A. Verbus (Counsel) - Attorney at Kirkland & Ellis LLP, Chicago, IL.
• Gregory S. Arovas (Counsel) - Attorney at Kirkland & Ellis LLP.
• Nathaniel DeLucia (Counsel) - Attorney at Kirkland & Ellis LLP.

Milwaukee Tool also has in-house counsel for intellectual property matters. Gregory Bollis serves as the Director of IP & Assistant General Counsel for Milwaukee Tool, leading their intellectual property legal team and managing their patent, trademark, copyright, and trade secret portfolios.