SCOTUS has routinely smacked down the notion of unlimited free speech without consequence. Hate speech is legal and generally allowed on public property as with any speech. Speech that incites violence against others is not.
So for instance it's legal in the US to say "Group X is subhuman and shouldn't be allowed to marry" but it's not oka to say "We should go murder Group X now.", especially when you have the means and motivation to do it. For instance while it is very common to make threats against the US president regardless of party, it's often seriously reviewed for obvious reasons and is not considered protected speech.
So for instance it's legal in the US to say "Group X is subhuman and shouldn't be allowed to marry" but it's not oka to say "We should go murder Group X now.", especially when you have the means and motivation to do it. For instance while it is very common to make threats against the US president regardless of party, it's often seriously reviewed for obvious reasons and is not considered protected speech.