The Alien Tort Statute decision had nothing to do with the compelling of documents and testimony. It had to do with interpretation of application to business and human rights. That's just to say it's not related to the compelling of documents and testimony.
In terms of the legitimacy of compelling documents and testimony, these are commonplace, normal practices. All of the provincial ombudspersons' offices in Canada, to my knowledge, have this power. Analogous offices across Canada do as well.
One thing to note—