We've written several posts about the Pennypack factors and how hard it can be to win a motion to strike in D. Del. The upshot is that it's often better to simply reach agreement on a curative remedy rather than spend time on full-blown motion practice.
Case in point: on Monday, Judge Burke denied a motion to strike a two-page supplemental expert declaration on a patentability issue. Applying the Pennypack factors, he concluded
that having to respond to the supplemental declaration (which, after all, relates to one discrete issue, and is only two pages long) would occasion some great prejudice to Defendants. The issue can be resolved by permitting Defendants to file a supplemental sur-rebuttal expert report on …