Discovery
Scope and Framework
Rule 26(e) requires timely supplementation of disclosures and responses where a party learns they are materially incomplete or incorrect, unless the information has otherwise been made known to the other parties.
It applies to expert reports and depositions as well.
Alternative Names:
Supplementation Duty, Rule 26(e) Duty
Why it Matters?
The consequence for failing to supplement is exclusion under Rule 37(c)(1), which operates automatically unless the failure was substantially justified or harmless. That makes supplementation a preservation issue rather than a courtesy, since evidence not disclosed cannot be used. The otherwise made known exception is narrower than parties assume, and courts have rejected arguments that a document produced somewhere in a large production satisfied it.
Frequently Confused with
Related terms
Frequently asked questions
What happens if a party fails to supplement?
Does production somewhere in the case satisfy the duty?
