Brant Gardner notes that Mormon has told his readers two important pieces of information about the Nephite legal system. The first is that the realm of law did not attempt to restrict belief: "Now there was no law against a man's belief; for it was strictly contrary to the commands of God that there should be a law which should bring men on to unequal grounds." (Alma 30:7) The second piece of information is that the law of the land was related to a scriptural basis: "For thus saith the scripture: Choose ye this day whom ye will serve" (Alma 30:8).
Now this Nephite law certainly applied to Korihor, but when Korihor preached in both Jershon and Gideon he was bound and brought before the judge. Isn't this a contradiction? Doesn't it appear that in these two cities they acted illegally?
While we do not understand the particulars of the Nephite law, there is a principle here that we can understand. While Korihor had the right to preach, the people of Gideon and Jershon had the right not to listen. It is quite probable that there was no law against the removal of a person from their midst. This would have been the legal implication of taking Korihor before the high priest and also the chief judge over the land. There was no apparent threat of punishment for Korihor's beliefs, but there was an apparently legal ability of the people to remove an unwanted influence from their community. The reader should note that the judge does not question, nor apparently concern himself with what Korihor believes. What the judge does ask is why Korihor is preaching these things. This is a subtle difference, which Korihor chooses to ignore in his response. The difference focuses not on the belief, but upon the actions to persuade others to adopt that belief. The Nephite law protects belief, but not the potential socially disruptive effects of preaching dissident ideas with the idea of fomenting fission in the society. [Brant Gardner, Book of Mormon Commentary, [http://www.highfiber.com/~nahualli/LDStopics/Alma/Alma30.htm], pp. 14-15]