The AD (CE) calendar made up by Dionysius Exiguus began on year one which corresponded to James the Just's day of birth. Like many he confused Jesus as his younger brother James. Jesus would be rolling over in his grave, assuming he did not resurrect, over this adoration of his arch rival. "Brother will betray brother to death" Matt 10:21.
In one of his books, Robert Eisenman has even given James the Just the position of the "Teacher of Righteousness" in the Habakkuk pesher. Thus, among the scholars who do not insist that this Dead Sea Scrolls pesher is from the time of Jonathan Maccabeus, James has now snatched away this position from John the Baptist who was more favored for it!
Part of the confusion is the "just" part of his name. Eusebius records that Clement of Alexandria related, "This James, whom the people of old called the Just because of his outstanding virtue, was the first, as the record tells us, to be elected to the episcopal throne of the Jerusalem church."
Yes, the second part appears to be true, since in Acts he is shown to be an important person in Jerusalem and on the side of Paul on the question of not requiring circumcision, but he was not "just", in fact he was always out to undermine Jesus. He was with Judas when Jesus was arrested in the Garden of Gethsemane being the one whose ear was cut off by Peter. (This was a metaphoric conflict about who would be the spokesman, "Ear" of Jesus.) Actually, after that he did relent to save his brother from death by joining the subterfuge of getting Jesus off the cross quickly to be revived. The name Joseph "of Arimathea" was used for him to obscure his change of heart to Caiaphas.
The problem that Jesus struggled with was that he was technically illegitimate being born when Mary and Joseph were merely betrothed, so that Caiaphas favored James over Jesus ("dragon did stand before the woman who is about to bring forth, that when she may bring forth, her child he may devour" (excommunicate). Rev 12:04). Mother Mary, with her rape by Joseph still in her mind ("And Mary said unto the angel, 'How shall this be, seeing a husband I do not know?'" Luke 01:34) also favored James who was born by mutual consent of husband and wife.
Before the Crucifixion Jesus had ridiculed him as the "Impotent Man at the Pool of Bethesda" waiting in vain for God's intervention on earth.
Jesus was a descendant of King David and thus his younger brother James, as the next in line after him, would be designated as crown prince, using the term "Justus". This was shortened to "Just". The verification of this is in the "Pesher of Christ" which shows that Jesus' first son was "Jesus who is called Justus" in Colossians 4:11 as a co-worker with Paul. He would be the true "Justus" when he reached adulthood replacing James.
Jesus had survived the Crucifixion, having merely fainted under the influence of a special poison administered to him on a reed. Having been revived without having his legs broken, he met with James (being called by the family name Cleopas) on the road to Emmaus. (Mary of Cleopas, the fourth Mary at the cross was the betrothed of James.) Since Jesus was intending to go back to the Essene monastery of Qumran (his "Ascension"), having fulfilled his obligation of having a child with Mary Magdalene, it was decided that he would abdicate from the David throne making James the David King. In this way the Church could pretend that Jesus had been resurrected. Technically this would have eliminated James' title of "Justus", the crown prince, however the apostles were not pleased.
When the council of the apostles met to replace Judas Iscariot, they showed their distrust for James (Joseph called Barsabas, who was surnamed Justus) by passing him over. They chose instead his younger brother Matthias (the Clementines say that this is Barnabas, having the name Joseph or Joses being 25 years old, the third son of Mary aged 25). (The name Barsabas is encountered in Acts 15:22 with Judas surnamed Barsabas being the fourth son of Mary and Silas being Simon the fifth son of Mary.) "Is not this the carpenter, the son of Mary, and brother of James, and Joses, and Judas, and Simon?" Mark 06:03.
This slap in the face for James meant that he would keep the title "Justus", at least until Jesus had a son. His younger brother Joses, who would have had the title of "Justus" if Jesus had died, would remain as Barnabas being "Son of Encouragement", third in the David line.
James was the leader of the Jewish Christians and was opposed by Peter and Paul. He had sway in Jerusalem only by default because Jerusalem was a hot bed of antagonism to the Christian Church. This was shown when Paul was almost stoned to death and put in prison there.
James was murdered by Ananus the Younger, the fifth son of Ananus the High Priest, in 62 AD. Ananus was an associate of Paul with the nickname "Demas" meaning people, being the representative of God to the people. (Ananus the Younger would later be killed trying to take the Temple back from the Zealots.) At that time, James had been included into the Church in an ecumenical spirit, but had clearly resorted to attacking Rome as his father did, which also got himself killed. This was at a time when War was imminent.
James' lack of importance is revealed by Peter in his Gospel of Mark for the three Women at the Cross where he give James the tongue-in-cheek title of "James the Less" (see the parallel with Matthew and John showing that these are Mary and her two sons James and Joses.)
Clearly, James does not deserve the reputation of "just". He and Jude where the siblings against Jesus, whereas Joses (Barnabas) and Simon (Silas) assisted Jesus and Paul. "And if a house be divided against itself, that house cannot stand." Mark 3:25