## Facts

- Multiple manufacturers and sellers of bar-code scanning and automatic identification products sought declaratory judgments regarding a group of patents assigned to Lemelson.
- The asserted patents related to machine vision and automatic identification bar-code technology and claimed priority to applications filed in 1954 and 1956.
- The patents issued after extended prosecution through long chains of continuations and continuation-in-part applications, with issuance occurring roughly 18 to 39 years after the earliest filings.
- Lemelson sent letters to customers of the manufacturers asserting infringement and implying licenses were required, creating commercial pressure and potential indemnity exposure.
- After a bench trial, the district court found the prosecution had been delayed through repetitive and unnecessary continuing filings, leaving the scope and status of the patents uncertain while the relevant industry developed.

## Issues

1. Whether the district court abused its discretion in holding the asserted patents unenforceable under prosecution laches based on unreasonable and unjustified prosecution delay and resulting prejudice.
2. Whether unenforceability for prosecution laches should apply to all claims of the asserted patents, not only the claims expressly analyzed by the district court.
3. Whether the appellate court needed to reach enablement and infringement issues if the patents were unenforceable.

## Decision

- The Federal Circuit affirmed that the asserted patents were unenforceable under the equitable doctrine of prosecution laches.
- The court held the district court did not abuse its discretion in finding an unreasonable and unjustified prosecution delay and prejudice to intervening public and private rights.
- The court extended the unenforceability determination to all claims of the asserted patents, not only the subset of claims discussed in detail below.
- The court declined to address enablement and infringement because unenforceability under prosecution laches was dispositive.

## Legal Principles

- Prosecution laches is an equitable doctrine that can render a patent unenforceable when an applicant’s unreasonable and unexplained delay in prosecution causes prejudice to others.
- The analysis is based on the totality of the circumstances, including the pattern and length of delay, the applicant’s justifications, and prejudice to intervening rights.
- Although continuation filings are permitted by statute, the right is not without equitable limits; serial continuations used to unreasonably and unjustifiably prolong prosecution may support prosecution laches.
- Prosecution laches may apply even when the prosecution conduct technically complies with statutory and regulatory requirements.
- When the delay and prosecution history infect the asserted patents as a whole, unenforceability may extend to all claims, not merely selected claims.

## Conclusion

The Federal Circuit affirmed that decades-long, unjustified prosecution delay through serial continuing applications can support prosecution laches, and it held the resulting unenforceability applied to all claims of the asserted patents because the same delayed prosecution history governed the patents in their entirety.


Symbol Techs., Inc. v. Lemelson Med., Educ. & Research Found., LP, 422 F.3d 1378 (Fed. Cir. 2005)