We've written several times about the Pennypack factors—the Third Circuit standard for determining whether to exclude late-disclosed evidence. Although the standard itself is fairly lenient (focusing on prejudice and whether it can be cured), the D. Del. judges have shown an increasing willingness to exclude evidence under Pennypack in recent years.
Earlier today, for example, Judge Stark applied Pennypack to preclude four witnesses from testifying at an upcoming jury trial (two from each side). The witnesses were disclosed months after the close of fact discovery, and Judge Stark refused to force the parties to use their limited trial prep time for clean-up discovery: "there is not sufficient time in the 12 remaining days before trial …