what is the penalty for threatening a Supreme Court justice?
Depends what your political affiliation is.
Lefties don’t go to prison.
18 USC 115 - Influencing, Impeding, or Retaliating Against a Federal Official by Threatening or Injuring a Family Member
18 U.S. Code § 871 - Threats against President and successors to the Presidency
Also includes judges. Makes you wonder why those celebs that threaten Pres. Trump are still walking around free. Oh, I forgot the DOJ is being run by Sessionszzzzzzzzzzzzzz.
Her tweet was more of a solicitation for murder, not a threat. Solicitation is the name of a crime that consists of a person offering money or inducing another to commit a crime with the specific intent that the person solicited commit the crime.
In 2014 for example, Lance Greenawalt was charged with one felony count of solicitation of murder against Adams County Court of Common Pleas President Judge Michael George. Greenawalt got sentenced to 10 to 20 years in the state pen.
“what is the penalty for threatening a Supreme Court justice?”
You get a book contract.
You get to spend some quality time with the US Marshall's Service.
“what is the penalty for threatening a Supreme Court justice?”
That depends. Left against right or right against left. In other words, do not try this, you would regret it.