In 1898, the Clines conveyed two lots to The First Presbyterian Church of Iowa City by warranty deed. The deed provided that 'if said church building is not erected on said premises within two years from Nov. 1st, 1898, or if erected and services shall be permanently discontinued, then said premises shall revert to the grantors or their heirs and assigns.' This condition was allegedly breached after July 4, 1965. The Presbytery of Southeast Iowa (P) acquired title to the land in 1970, and filed this quiet title action in 1971, naming the heirs of the Clines (D) as defendants. P claims that D's reversionary interest in the property was extinguished under a statute which provides that 'No action based upon any claim arising or existing by reason of the provisions of any deed or conveyance or contract or will reserving or providing for any reversion, reverted interests or use restrictions...shall be maintained either at law or in equity...after twenty-one years from the recording of such deed...unless the claimant...shall file a verified claim with the recorder of the county wherein said real estate is located within said twenty-one-year period. In the event said deed was recorded...more than twenty years prior to July 4, 1965, then said claim may be filed on or before one year after July 4, 1965.' D contests the validity of the statute on constitutional grounds.