Philipp, thanks for this thoughtful comment. Here are some thoughts on your points.

I think you might have expected too much from the Supreme Court: if it had taken the case, it likely would have taken it to decide whether a private party has standing to bring a claim for purely equitable relief under RICO, not to decide broader points about comity.
I don’t think the decision is advisory—certainly it’s not advisory in the technical sense. Your rhetorical question about the preclusive effect of the judgment in other countries is, as Alex Manevich put it in an earlier comment, the “$9B question,” but it’s really a question of Canadian law. So if a Canadian court ultimately gives preclusive effect to Judge Kaplan’s findings of fact, perhaps the criticism would be more usefully directed to its decision rather than to Judge Kaplan’s decision.
You raise a good and interesting point about whether Chevron stood to suffer injuries in the United States in light of the LAPs’ disavowal of any intention to seek recognition of the Ecuadoran judgment here. This is a timely question in light of RJR Nabisco. But this kind of argument cuts both ways. The Ecuadoran judgment runs against the US entity, but the LAPs are seeking recognition and enforcement in Canada against the Canadian indirect subsidiary, which is not the judgment debtor. So on the flip side of your argument one could ask why the LAPs aren’t seeking recognition here, and one could also say that it’s the LAPs, not Chevron, that is trying to pierce the corporate veil.
The overarching concern, I think, is that Judge Kaplan was purporting to act as a kind of world “super-court.” I understand the motivation for this concern. I think that with respect at least to Donziger himself, the concern is misplaced, since it seems right that a US court could determine that it is inequitable given the findings of fact for Donziger, whose domicile is here, to profit from the Ecuadoran judgment. The issue is sharper with respect to the LAPs. As I recall, the injunction only runs against the two representatives of the LAPs whom the judge found were within the court’s personal jurisdiction. So perhaps that concern is not too pressing. In any case, as a doctrinal matter, assuming the correctness of the personal jurisdiction (which could very well be wrong, although I don’t recall it being a focus of the appeal), I can’t see anything wrong with an injunction directed at those two individuals.

Alex, thanks for this comment. I don’t think the conflict is between the US judgment and the Ecuadorian judgment. I think the potential conflict is between the US judgment and the forthcoming arbitration award, which might take a different view on the corruption. Then we would indeed face a difficult problem!

Should US courts really be allowed to question foreign judgements, even if there is no attempt to collect the foreign judgement in the US?

Should US courts really be allowed to issue advisory opinions with preclusive effect to sovereign courts of other countries?

And did there really occur a domestic damage to Chevron US within the USA? The LAPs do not target Chevron US. They target foreign subsidiaries that are legally independent from Chevron US. So is a damage to a legally independent, foreign subsidiary really a damage to Chevron US? To come to that conclusion one has to pierce the corporate veil of the subsidiary.

Another problem in my view is that Chevron US was the claimant in the US RICO action, but not its subsidiaries. The constructive trust was instituted in the favor of Chevron US, but not in the favor of its subsidiaries that took no part in the US proceedings. So, what happens if the LAPs are successful in the enforcement proceedings in Canada against Chevron Canada? Can the constructive trust claim reimbursement for that, too? I do not believe that Judge Kaplan had the power to institute a constructive trust in the favor of a foreign subsidiary that is legally independent from Chevron US and that was not party to the US proceedings.

So what happens in the Ontario Lago Agrio judgment enforcement proceedings when Chevron raises the US judgment in its defence, pitting the two foreign judgments against each other? I have no idea, but I’m certainly eager to find out!