Background
Jerome Lemelson was arguably the most prolific practitioner of what patent lawyers call “submarine patents.” Beginning in the 1950s, Lemelson filed patent applications on inventions in manufacturing, machine vision, and bar code reading. He then filed a long series of continuation and continuation-in-part applications, keeping the applications pending in the Patent and Trademark Office for decades while industries unknowingly built their businesses on technology similar to his claimed inventions. When the technology became commercially valuable, Lemelson “surfaced” the patents — allowing them to issue — and then demanded royalties from manufacturers who had independently developed the same technologies.
The Lemelson foundation eventually claimed that bar code scanners and machine vision systems used in manufacturing violated Lemelson’s patents, which claimed priority back to applications filed in 1954 and 1956. Because the old patent laws calculated patent term from the issue date (not the filing date), a patent that filed in 1954 and issued in 1990 would have a full 17-year term from 1990. This created a profound unfairness: companies that independently invented and commercialized technologies while the applications were secretly pending would suddenly find themselves infringing 40-year-old claims.
Symbol Technologies and other companies sued for a declaration that the Lemelson patents were unenforceable. The district court held that prosecution laches — an equitable doctrine barring enforcement of patents filed after unreasonable delay — was not available as a matter of law under the then-current state of patent jurisprudence. Symbol appealed.
The Court’s Holding
The Federal Circuit reversed the district court, holding that the equitable doctrine of prosecution laches is available as a defense to patent enforcement and can bar claims that issued after an unreasonable and unexplained delay in prosecution. The court held that the doctrine was not abolished by the 1952 Patent Act or subsequent amendments and remained a valid equitable defense grounded in the principle that equity protects against unconscionable uses of legal rights.
The court noted the significant prejudice that unreasonable prosecution delay can cause: when a patent applicant deliberately keeps applications pending for decades while technology industries develop in ways that might infringe the pending claims, and then asserts the patents after enormous capital investment, the equitable defense of prosecution laches may render the claims unenforceable. The court remanded to the district court to apply the doctrine to the specific Lemelson patents.
On remand in 2004, the district court found that Lemelson’s 18-to-39-year delays in prosecuting the claims were unreasonable and unexplained, and held the asserted patents unenforceable. The Federal Circuit affirmed that decision in 2005.
Key Takeaways
- Prosecution laches is a viable equitable defense that can render patent claims unenforceable when the patentee unreasonably and inexplicably delayed prosecution while the relevant industry developed.
- Patent applicants have an obligation not to unreasonably delay prosecution in ways that prejudice the public and competitors who develop technology without notice of pending patent claims.
- The submarine patent strategy — keeping applications pending for decades to exploit continuity-based priority while industries develop — can be barred by equitable defenses.
- Prosecution laches does not require proof of subjective bad faith; unreasonable delay plus prejudice to accused infringers can suffice.
- The 2002 change in patent law computing terms from filing rather than issuance largely eliminated submarine patents going forward, but prosecution laches remained relevant for pre-1995 applications.
Why It Matters
Symbol Technologies v. Lemelson was a landmark ruling in the campaign against submarine patents — a patent strategy that had cost American industry billions of dollars in unexpected royalties. Jerome Lemelson’s foundation had collected over $1.5 billion in royalties by exploiting the old patent term system, and his bar code and machine vision patents were particularly notorious. By reviving the prosecution laches defense, the Federal Circuit provided the legal mechanism for accused infringers to escape enforcement of patents that had been kept pending for unconscionably long periods.
The case has lasting doctrinal significance beyond the Lemelson litigation. Prosecution laches remains available today as a defense in cases involving unreasonably delayed continuation practice. As continuation applications continue to be used strategically in patent prosecution, Symbol Technologies provides the equitable counterweight to practices that prejudice competitors and the public. The ruling also contributed to broader reforms in patent prosecution practice, reinforcing the trend toward requiring prompt prosecution and timely disclosure of pending patent claims.