In Fain Land & Cattle Co. v. Hassell, 163 Ariz. 587, 596, 790 P.2d 242, 251 (1990), the question before the court was whether exchanges of school trust lands for non-trust lands violated either the Enabling Act or the Arizona Constitution. 163 Ariz. at 590-92, 790 P.2d at 245-47. The supreme court concluded the exchanges were explicitly authorized by an amendment to the Enabling Act and therefore did not violate the Act. Id. at 592, 790 P.2d at 247. However, the court determined that the exchanges violated Arizona's constitution because it had not been similarly amended. Id. at 593, 790 P.2d at 248. Then, in considering whether its decision should be applied retroactively, the court noted that only those conveyances which do not comply with the Enabling Act are void, and therefore it was "not required . . . to nullify past exchanges" because they did not violate the Enabling Act. Id. at 596, 790 P.2d at 251.