
Many District of Delaware scheduling orders in patent cases include deadlines for both "initial" and "final" infringement and invalidity contentions. In those cases, parties often argue that having a deadline for "final" invalidity contentions means there is no obligation to supplement in the period between initial and final contentions.
The obligation to supplement under Federal Rule of Civil Procedure 26, after all, states that it applies to Rule 26(a) disclosures, interrogatories, RFAs, and RFPs—but not explicitly to "contentions" required by a scheduling order.
I've seen the Court go both ways on this. The judges often seem willing to grant a motion to compel earlier responses, saying that early supplementation is required …