WhereIsAtlas · Law

Bose v. JBL

Bose sued JBL and Infinity over a loudspeaker port shaped like an ellipse — and won $5,676,718.32 in a case that turned on one conic section

Concluded — Bose Corporation sued JBL, Inc. and Infinity Systems Corporation in the US District Court for the District of Massachusetts in 1998, alleging infringement of US Patent No. 5,714,721, which covers the shape of a loudspeaker's port opening. The court found no literal infringement but infringement under the doctrine of equivalents, and awarded Bose $5,676,718.32. The Federal Circuit affirmed on 17 December 2001. The case is cited in patent-damages literature for upholding a royalty based on the entire value of the loudspeaker rather than the port alone.

A loudspeaker enclosure is not a solid box. Most designs contain a port — a tube that lets acoustic energy from inside the cabinet radiate outward, which is what allows a small speaker to produce useful bass. The design of that tube is critical, because a badly shaped port produces audible chuffing and distortion rather than sound.

Bose Corporation owned US Patent No. 5,714,721, titled "Porting," covering an invention by two Bose employees, Brian Gawronski and Gerald Caron. The patent's key claim described a loudspeaker port with a smoothly flared input and output, where the boundary around the port is "defined by an ellipse having a major diameter." In plain terms, the claim was about a port opening shaped like an ellipse rather than a circle.

Bose brought suit against JBL, Inc. and Infinity Systems Corporation — two loudspeaker brands that would both later come under the same corporate owner, Harman International. Bose argued that JBL's enclosures using a "Linear-A" curve or an "Exponential" curve incorporated the patented port technology. Eleven models were named, including the N24, N26, N28, N38, ND310, S26, S38, S312, SCS125, ESC300B and ESC350.

The case went to Judge Patti B. Saris in the District of Massachusetts. The district court granted JBL summary judgment of no literal infringement — meaning the accused ports were not exactly what the patent described — but refused to dismiss the claim under the doctrine of equivalents, which covers devices that do the same job in a substantially similar way. After a bench trial, the court entered judgment for Bose and awarded damages of $5,676,718.32.

JBL appealed to the US Court of Appeals for the Federal Circuit on three grounds. The most legally interesting was prosecution history estoppel. During the patent's prosecution, Bose had amended its claim to add the words "having a major diameter." Under the doctrine of prosecution history estoppel, a claim narrowed during prosecution generally cannot later be expanded through the doctrine of equivalents. JBL argued that the amendment narrowed the claim and therefore closed off equivalence.

The Federal Circuit disagreed, and the reasoning is memorable: an antecedent-basis objection had required Bose to add the phrase, but an ellipse inherently has a major diameter, so the amendment did not narrow anything. In the court's words, "there can be no dispute that mathematically an inherent characteristic of an ellipse is a major diameter." The court applied the en banc Federal Circuit decision in Festo while noting that the Supreme Court had granted certiorari in that case — placing this ruling right at the hinge of a major shift in US patent law.

JBL's second argument was evidentiary. It wanted to introduce a French patent application, the Dehaeze reference, to prove the patent invalid. The district court excluded it, having found that Dehaeze disclosed a hyperbola, which differs from an ellipse "in both shape and mathematical formula." The Federal Circuit held that excluding the reference was not an abuse of discretion.

The third argument was about money, and it is why the case is still cited. JBL argued that the royalty had been calculated on the entire value of the loudspeaker systems rather than on the port, a small component. The Federal Circuit upheld the award under the "entire market value rule," which permits damages based on the whole apparatus when the patented feature is the basis for customer demand. The court noted that the patented port worked inextricably with the other components as a single functioning unit, that it eliminated port noise and improved bass response, and that a JBL marketing executive had acknowledged improved bass performance was a prerequisite for proceeding with certain models.

The judgment was affirmed. Bose was represented by Fish & Richardson; JBL by David Boies of Boies, Schiller & Flexner, alongside Jones, Day, Reavis & Pogue.

Timeline

  1. 1996 — The patent issues: US Patent No. 5,714,721, "Porting," issues to Bose on an invention by Brian Gawronski and Gerald Caron, covering a port bounded by an ellipse.
  2. 1998 — Bose files suit: Bose sues JBL and Infinity Systems Corporation in the District of Massachusetts over the shape of the port. (Boston, MA)
  3. 2000 — No literal infringement, but equivalents survive: The court grants JBL summary judgment of no literal infringement but denies it on the doctrine of equivalents.
  4. 31 Aug 2000 — Judgment for Bose: After a bench trial, the court enters judgment for Bose.
  5. 12 Sep 2000 — Damages set: Judgment is entered for Bose in the amount of $5,676,718.32.
  6. 17 Dec 2001 — Affirmed on appeal: The Federal Circuit affirms, holding that adding "having a major diameter" did not narrow the claim because an ellipse inherently has one.

Quick facts

Plaintiff
Bose Corporation
Defendants
JBL, Inc. and Infinity Systems Corporation
Patent
US Patent No. 5,714,721, titled "Porting"
Inventors
Brian Gawronski and Gerald Caron, both Bose employees
The claim at issue
a loudspeaker port bounded by "an ellipse having a major diameter"
Accused technology
ports using a "Linear-A" curve or an "Exponential" curve
Models named
N24, N26, N28, N38, ND310, S26, S38, S312, SCS125, ESC300B, ESC350
Court
US District Court for the District of Massachusetts, Judge Patti B. Saris
Damages awarded
$5,676,718.32
Appeal
US Court of Appeals for the Federal Circuit, No. 01-1054
Decided
17 December 2001
Result
affirmed
Key holding
the amendment adding "having a major diameter" did not narrow the claim, because an ellipse inherently has one
Why the French reference failed
Dehaeze disclosed a hyperbola, not an ellipse
Damages principle upheld
the entire market value rule
Counsel
Fish & Richardson for Bose; Boies, Schiller & Flexner and Jones Day for JBL

Lineage — where the name went

A patent about the shape of a hole, and the chain from an invention by two Bose engineers to a $5.68 million judgment against a rival speaker maker.

  1. Brian Gawronski created US Patent 5,714,721 (named as co-inventor)
  2. Gerald Caron created US Patent 5,714,721 (named as co-inventor)
  3. Schreiber created US Patent 5,092,424 (the earlier patent in the family)
  4. US Patent 5,092,424 was ancestor of US Patent 5,714,721 (the '721 is a continuation-in-part)
  5. Bose Corporation created US Patent 5,714,721 (owner of the patent)
  6. 2001 — Bose Corporation defeated JBL, Inc. (judgment of $5,676,718.32 affirmed on appeal)
  7. 2001 — Bose Corporation defeated Infinity Systems Corporation (co-defendant in the same action)
  8. JBL, Inc. sibling-of Infinity Systems Corporation (both became Harman International brands)
  9. JBL, Inc. defeated The Dehaeze reference (the reference was excluded as disclosing a hyperbola, not an ellipse)
  10. Festo Corp. v. Shoketsu created The judgment (the estoppel standard applied to Bose's claim amendment)
  11. The judgment was succeeded by US Patent 5,714,721 (the outcome that closed the dispute)
  12. 2001 — Judge Patti B. Saris created The judgment (presided over the bench trial that produced the award)

Entities in this tree: Bose Corporation (company); Brian Gawronski (person); Gerald Caron (person); Schreiber (person); US Patent 5,092,424 (product); US Patent 5,714,721 (product); JBL, Inc. (company); Infinity Systems Corporation (company); The Dehaeze reference (product); Festo Corp. v. Shoketsu (event); The judgment (event, 2001); Judge Patti B. Saris (person)

Sources

  1. Bose Corporation v. JBL, Inc. and Infinity Systems Corporation, 274 F.3d 1354 (Fed. Cir. 2001) — Public.Resource.Org (2026-09-19)
  2. Bose Corporation v. JBL, Inc. and Infinity Systems Corporation — CourtListener (2026-09-19)
  3. Assessing Patent Infringement Damages — Morgan Lewis (2026-09-19)

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