When Free Speech Becomes Harbinger for Violent Acts

As arguably the most precious of American rights, the first amendment right to free speech since has, since its inception, long been debated as to where the line exists.
And with political tensions at seemingly all time highs in the U.S., it also has become the justification for language inciting violence and breeding hate.
Recent tragedies have further propelled the debate into the spot light as over the last year in several high profile acts of violence, the perpetrators had previously spoken of their intent to cause harm to those with whom they disagree.
This prevents a difficult conundrum for law enforcement and begs the question for us all- must we wait until its too late for someone's speech to become part of the crime?