The Supreme Court will explore the limits of "speech crimes" in the Internet age, especially laws aimed at protecting those harassed or bullied online.
The justices will hear oral arguments this fall in the prosecution of Anthony Elonis over Facebook posts.
Some were in the form of rap lyrics, which Elonis said were "therapeutic" for dealing with emotional pain.
But the federal government alleges he crossed a line and used threatening language about his estranged wife and an FBI agent investigating him.
"Did you know that it's illegal for me to say I want to kill my wife?" Elonis wrote. "It's illegal. It's indirect criminal contempt. It's one of the only sentences that I'm not allowed to say."
The justices will decide the level of proof needed to convict someone for making criminal threats.
The issue in play here has broader implications for free speech amid the explosion of popular and often anonymous social media.
Key questions here involve whether sites like Twitter are in the same category as more conventional news links, and are general threats made online different than those made in person?