New York federal judge Lewis Kaplan ruled last week that Chevron may “conduct discovery” regarding a $6.4 million contract between the government of Ecuador and MCSquared, a Brooklyn, N.Y., public-relations firm. Score another victory for the oil company over plaintiffs seeking to blame it for environmental damage in the Ecuadorean jungle.

MCSquared “likely possesses evidence relating to the coordination between the Republic of Ecuador and the plaintiffs behind the fraudulent lawsuit,” Chevron said in a statement on Nov. 24....