There was plenty of drama when Chevron Corporation’s fraud and racketeering case against Steven Donziger finally went to trial last fall. But few moments were as memorable—or as illuminating—as when Randy Mastro ambushed a former Ecuadorean judge about the $9.5 billion environmental judgment at the heart of the case.

The judge, Nicolas Zambrano Lozada, issued the megajudgment under his name in Ecuador in 2011. But under oath in a Manhattan courtroom, peppered with Mastro’s nonstop questions, Zambrano appeared to know very little about his own ruling. The failed pop quiz seemed to perfectly support Chevron’s allegations: that Donziger and his team rigged the underlying pollution case in Ecuador, from fixing a supposedly independent damages report to bribing a judge and ghostwriting the final judgment itself.