The Marshalls (defendants) entered into a land contract as vendees. The land contract contained a provision that afforded the vendor an optional right to terminate the contract upon any breach of the contract terms continuing for a period of 30 days. The contract also contained a clause affording the vendor a right to claim any sums paid on the contract as liquidated damages in forfeiture if a claimed breach were not remedied within 30 days. During the vendor’s lifetime, the Marshalls made payments on the land contract at irregular intervals. The Marshalls stopped making payments on the land contract approximately two years after the vendor’s death. At the time of their last payment, the Marshalls had paid $21,000 toward the principal balance and owed $15,000 on the remaining balance. Skendzel (plaintiff) and others acquired interests in the land contract as assignees of the vendor’s estate. Skendzel brought suit to enforce the forfeiture provision of the land contract and assert possession of the property. The trial court denied Skendzel’s claim. The court of appeals reversed the trial court decision, holding that Marshall had breached the terms of the contract and that the vendor had not waived the forfeiture provision. Marshall appealed.