The passage in question (Matthew 5:22) carries forth from the preceding verse, Matthew 5:21. Our Lord goes deeper than murder to the cause of murder, anger. Anger is murder in the mind (1 John 3:15), so Jesus teaches that a similar fate awaits the angry person as awaits the murderer.
In Matthew 5:22 it moves from the local court implied in verse 21 of twenty-three members adjudicated serious crimes like murder to the supreme court of the land, the Sanhedrin, to the ultimate court, the judgment seat of God. The Aramaic loanword, raca, was used to insult a person, roughly equivalent to "idiot" or "empty-headed fool." "Fool" was the Greek equivalent, also used as an insult, meaning "fool," though Jewish readers might think of the Hebrew moreh, referring to apostasy or wickedness. The two terms were fairly equivalent in their thrust, referring to contempt for another (a type of anger).
Jesus’ point is a person demonstrating such behavior is leading to judgment both on the earthly and the heavenly planes. Moreover, it is clear here that name-calling is at the core of showing angry contempt.
AMR