Is it necessary to limit or put restrictions on freedom of thought and expression?

Okay, this topic really bothers me. Some people are arrested for speaking their own opinion about the autority or government yet our FIRST AMENDMEMT clearly states that we have a freedom of speech. Might as well be striped from our freedom is this is happening. BECAUSE how are people going to set amendments that give us our rights and discussing about our unalienable rights saying that it cannt be taken away from us yet so many people are put into jail for it. I don't think they should put a limit on the freedom of thought and expression because they have a mouth to speak what they choose of their choice. No one can stop them from speaking what they believe in.