This research is motivated by the prevalence of Sale and Purchase Deeds (AJB) that formally meet requirements yet suffer from legal defects due to deceit, identity fraud, or procedural violations by the Land Deed Official (PPAT). The validity of an AJB as an authentic deed is crucial for the lawful transfer of rights and serves as the basis for issuing the Certificate of Ownership (SHM). When an AJB is legally defective, legal certainty regarding the land is compromised, potentially leading to protracted disputes. This study aims to analyze the legal certainty of rights transfers based on legally defective AJBs.