Cofty...The pericope has been long interpreted by the Catholic Church as a proof text for a central authority. Churches like the WT repeat this claim. However, reading the text without this coloring reveals something very different.
The story starts with Paul and Barny going to Antioch church and there they encounter Pharisee Xtians from Jerusalem (15:24) contradicting the doctrine held by the Antioch church. The church leaders in Antioch send Paul and Barnabus to go to the church these guys were from (Jerusalem) and find out if they had in fact sent them with what was deemed heretical doctrine. They are greeted and a short airing of opinions ensues. Then the leaders of the Jerusalem church make clear they in fact had not sent the guys and they did not agree with them (again 15:24). Then James declares his opinion is that the Pharisee brothers needed to accept the changes but at the same time thought it best if the Antioch church would accommodate the Jewish Xtians on matters that they regarded as "essential/necessary" The Jerusalem church then sent 2 guys along with Paul and Bany back to Antich to ensure the relationship between churches was back on track.
The purpose this story was created was to create the impression that these powerful churches had in fact been unified at an early date (6:5 also) not to suggest Jerusalem was in control. However soon after that is how the catholic church used it to support the role of Rome and the apostolic succession doctrine. BTW, Paul effectively denies this ever took place in Gal 2 for instance.
The long Catholic tradition has influenced the interpretation of this story. It has also influenced the translating with words like "commanded" rather than 'Instructed' and James saying I "judge" rather than 'in my opinion'. (Unless we are conceding James was in charge of all Xtians)
As an aside, this pericope has many textural variants. A number of manuscripts changed the list of necessary things or preserved an older form. And what also cues me editing is involved is the simple change from a definite article before each item in the list in verse 20 to no articles in 29. A small thing but reflecting a different hand IMO.