The law of the land is the law- דִּינָא דְמַלְכוּתָא דִּינָא TB Nedarim 28 part two

Shmuel’s halakhic principal “the law of the land is the law-dina demalkhuta dina-דִּינָא דְמַלְכוּתָא דִּינָא” found on today’s daf TB Nedarim 28 needs further explication. This principle has many different applications in various areas of Jewish law and due to the many countries Jews have lived in. The sages have weighed in on its implications and ramifications. There are those who believe that this principle only applies to a Gentile king for he is permitted to enact laws because the land is his. He may decide who may reside in his land and who may not. Conversely this principle does not apply to the kings of Israel at all because Israel's right to the land of Israel is not dependent upon the king. (Ran on our daf ד"ה בְּמוֹכֵס הָעוֹמֵד מֵאֵלָיו)

This is not the opinion of Rambam and the Ritba. They hold that this principle derives from the power of kingship in general whether the king is a Jew or a Gentile. The Rosh holds the power of this principle is only applicable to those who wish to live in that specific country or those who wish to cross it. In these cases the kingdom has the right to collect taxes from these people; however, this does not apply to those who do not intend to be in that place at all. Most of the commentators and poskim follow Rebbeinu Tam’s approach. The obligation to obey the laws of the land only apply to laws where everybody is equal under the eyes of this law. If the king discriminates against a certain group or against a specific individual the laws of the land do not apply. He calls this discrimination legal thievery גזלנתא דמלכותא. The Ritba holds that this principle “the law of the land is the law” only applies to ancient laws and not to any new laws a king may enact.

The principal is codified in in the Shulkhan Arukh, Hoshen Mishpat, 369:2, 7-9.