In May 2000, Campbell, along with Michael de Jong and Geoffrey Plant, brought a court case against the Nisga'a Nation, the Attorney General of Canada and the Attorney General of British Columbia, parties to the first modern day Aboriginal Treaty in British Columbia, known as the Nisga'a Final Agreement. He and the other plaintiffs claimed the treaty signed with the Nisga'a Nation was "in part inconsistent with the Constitution of Canada and therefore in part of no force and effect". However, Justice Williamson dismissed the application, judging that the enacting legislation did "establish a treaty as contemplated by Section 35 of the Constitution Act, 1982. The legislation and the Treaty are constitutionally valid."