Chevron, who through a coup controlled the Ecuadorian government for many years, got the government to sign a law called “The Act of Liberation”, which, although very much contradicting the name, made it impossible for anyone (especially indigenous people) to sue the oil company.

They made it illegal to be sued.

(due to being rightfully questioned about my, and the video's, source on this, I've done some of my own source checking and found this exact court document, for anyone curious)