## Facts

- Micron entities sued Rambus, and Rambus counterclaimed, in a dispute over Micron’s alleged infringement of twelve DRAM-related patents.
- Rambus implemented a company-wide document destruction program that included scheduled “shred days” beginning in 1998, during which paper and electronic materials were destroyed.
- The destruction occurred after Rambus had developed and refined a strategy to enforce its DRAM patent portfolio through litigation against DRAM manufacturers, including Micron.
- Materials destroyed included documents relevant to Rambus’s licensing and enforcement strategies, standards-setting (JEDEC) activities, and patent prosecution—topics central to Micron’s defenses and counterclaims.
- After a 2007 bench trial on spoliation and unclean hands, the court previously found spoliation and sanctioned Rambus by holding the asserted patents unenforceable against Micron.
- The Federal Circuit later vacated in part and remanded for more detailed findings regarding the timing of Rambus’s preservation duty, bad faith, prejudice, and the appropriateness of the sanction.

## Issues

1. When did Rambus’s duty to preserve evidence arise—i.e., at what point was litigation reasonably foreseeable?
2. Whether Rambus destroyed documents in bad faith, with a litigation purpose, after the duty to preserve attached.
3. Whether the destruction prejudiced Micron’s ability to litigate its defenses and counterclaims.
4. What sanction, if any, was warranted, and whether patent unenforceability was appropriate as compared to lesser sanctions.

## Decision

- The court held that litigation against DRAM manufacturers was reasonably foreseeable before the principal destruction events, triggering Rambus’s duty to preserve evidence.
- The court found Rambus engaged in bad-faith spoliation, including litigation-driven and selective destruction intended to impair Micron’s case.
- The court found the spoliation caused actual, substantial prejudice because the destroyed documents were highly probative on central issues and could not be reconstructed from other sources.
- The court reaffirmed the sanction that the twelve patents-in-suit were unenforceable against Micron.

## Legal Principles

- A duty to preserve arises when litigation is reasonably foreseeable, not only after a complaint is filed.
- Bad faith may be shown where document destruction is litigation-driven, selective, and designed to remove harmful evidence while retaining favorable materials.
- A spoliation sanction must be tied to prejudice; where missing evidence is central and irreplaceable, prejudice may be substantial.
- Case-terminating sanctions may be imposed when bad-faith spoliation and resulting prejudice cannot be adequately addressed through lesser measures such as adverse inferences or monetary sanctions.

## Conclusion

On remand, the court determined that Rambus anticipated litigation, destroyed relevant evidence in bad faith, and substantially prejudiced Micron; it therefore reimposed the severe sanction of unenforceability of the asserted patents against Micron.


Micron Tech., Inc. v. Rambus Inc., 917 F. Supp. 2d 300 (D. Del. 2013)