Q: In some places, the law of the land stipulates that real-estate transactions are effective only upon registering the change in the land registry. If I purchased land with classic kinyanim, is the sale effected?
A: The Mishnah (Kiddushin 26a) teaches that land is acquired through monetary payment, sale document, or act of possession. Real-estate transactions with non-Jews are concluded only with a sale document (C.M. 194:2).
Nonetheless, the Gemara (B.B. 54b) teaches that if the law of the land stipulates that possession of the land is effected only in a certain manner, the law is binding based on dina d’malchusa.
Chazon Ish (C.M., Likutim #16) addresses the issue of selling land for the purpose of Shemittah, maaser or mechiras chametz, which is not registered in the land registry. He maintains that dina d’malchusa does not preclude judging according to halachah if the parties stipulate to finalize the transaction in the normal halachic manner. Others disagree, since the law is for the welfare of society (Pischei Choshen, Kinyanim 2:; 12:5).