Q: What is the basis of dina d’malchusa dina?
A: This rule is generally assumed to be Biblical, although some indicate that it is Rabbinic (Responsa Chasam Sofer, Y.D. #314; Beis Shmuel, E.H. 28:3).
There are a number of possible sources:
1. The Noahide mitzvah of dinim (law; Rashi, Gittin 9b).
2. The populace accepts the laws of the king willingly, even if not explicitly (Rashbam, B.B. 54b; Terumas Hadeshen #341).
3. The land belongs to the king, and he has the right to evict or expel if he wants to; he intends that even citizens who own land should dwell only according to his rules (Rosh Nedarim 3:11; Ran Nedarim 28a).
4. The king has ownership of his subjects (kibbush; Rashba, Yevamos 46a; Chazon Ish, Likutim, C.M. 16:9).
5. Akin to hefker beis din hefker (Rabbeinu Yonah, B.B. 54b; Chavos Daas, Y.D. 165:5).
6. The ‘law of the king’ stated in Parashas Shoftim, which extends also to non-Jewish kings (Mabit, Kiryas Sefer, Hil. Gezeilah 5:18).
There are various practical differences that emanate from these different sources.