Responsa על בבא בתרא 12:5

Q. A was pursuing his craft in town T when B began to pursue the same craft. A demanded that a ban be issued [in accordance with the talmudic law of competition] against any one besides himself who will engage in that craft. B, however, restrained him from such action until a decision, as to the legality of such a ban, be issued by a Rabbi. Subsequently A bribed the ruler of the town who issued a decree forbidding anyone, but A, to pursue that particular trade. A again demanded the issuance of a ban, claiming that the Jews are bound to abide by the law of the secular government. B, however, objected to the issuance of such a ban until a decision was rendered by a Rabbi.
A. If B is a resident of A's town,^*The author uses the term Bar-meboo, a resident of A’s alley, but he is only using the talmudic expression. The decision, however, is that in his own house B may pursue any craft he wants; while A may restrain B from settling next to A and pursuing A’s craft. A can not restrain him from pursuing his craft. The secular government, according to Jewish law, has no jursidiction over trade competition; therefore, the Jews are not bound to abide by their decree in such matters.
SOURCES: Pr. 677.