> Through a controversial discovery process, Chevron obtained, among other things, Donziger’s private diary entries. But the company’s central piece of evidence was the testimony of their sole witness: Alberto Guerra, a disgraced Ecuadorian judge who’d been removed from the bench over allegations of corruption and who had accepted hundreds of thousands of dollars and other benefits from the company. After meeting with Chevron’s lawyers 53 times, Guerra testified that Donziger and his team had offered the judge in the original trial a $500,000 bribe and had ghostwritten the 2011 decision against Chevron. In a related case three years later, he admitted he had lied in his testimony.

Maybe because of the above?

Indeed, it seems pretty clear that the position of the article is that Guerra lied in US court in order to bolster Chevron's case.

Maybe, but again, the article doesn't really explain. Is this the author's research, a statement the author was able to confirm, or just Donziger's unconfirmed characterization of how the case went?

Maybe if you read the article and follow the provided links, it would be revealed to you ;)