In La Salle National Bank v. County Board of School Trustees, 61 Ill. 2d 524, 337 N.E.2d 19 (1975), the supreme court described the preclusive effect of a condemnation judgment. In La Salle National Bank, two school boards sought to sell land they acquired in separate eminent domain proceedings but later decided not to use for the purpose for which it was condemned, i.e., as sites for schools. The plaintiffs, banks that held the properties as trustees at the time they were condemned, filed suit to stop the sales, alleging that they retained a reversionary interest in the properties that was triggered when the school boards decided not to use them for school purposes. The supreme court held that the plaintiffs' claims were barred under the doctrine of res judicata: "Plaintiffs had the opportunity to contend in the eminent domain action that the school authorities would take less than a fee simple estate but did not do so. No appeals were taken from those final judgments. The judgments are not now subject to collateral attack. Plaintiffs cannot litigate the question they could have had decided in the original proceedings." La Salle National Bank, 61 Ill. 2d at 530-31.