For Paul, it wasn't a question. He didn't go to get a decision. Instead, he went to make them see that he was not wrong, and that he was doing what he was entrusted by the Lord to do.
Gal 2:2: "I went up as a result of a revelation, and I presented to them the good news that I am preaching among the nations. This was done privately, however, before the men who were highly regarded, to make sure that I was not running or had not run in vain."
Gal 2:4-5: "But that matter came up because of the false brothers brought in quietly, who slipped in to spy on the freedom we enjoy in union with Christ Jesus, so that they might completely enslave us; 5 we did not yield in submission to them, no, not for a moment, so that the truth of the good news might continue with you.
Gal 2:6: "But regarding those who seemed to be important—whatever they were makes no difference to me, for God does not go by a man’s outward appearance—those highly regarded men imparted nothing new to me. "
The letter sent out by those in Jerusalem starts out almost as an apology:
"The apostles and the elders, your brothers, to those brothers in Antioch, Syria, and Ci·liʹcia who are from the nations: Greetings! Since we have heard that some went out from among us and caused you trouble with what they have said, trying to subvert you, although we did not give them any instructions..."
Keep in mind that it WAS a decision from Jerusalem. It's even referred to as such in Acts 21:25. But, it HAD to come from there since that was where the JEWS originated from, and this Christianity thing was originally from the Jews. Paul was seemingly teaching an apostasy from Moses, so there was disruption (Acts 21:21). And that disruption was causing a problem. So, there needed to be some decision from somewhere. It wasn't a centralized body, though. It simply was from the place that was central to the Jews, and since the nations were starting to be gathered in, it makes sense that a decision came from the Jews there regarding that particular matter. After all, it was FROM there that false brothers were insisting that ones get circumcised.
Now if there truly was a centralized body in Jerusalem, then why was Paul sent out from Antioch on all three of his missionary journies? And why was it in Antioch that the name "Christian" was first used "by divine providence"? (Acts 11:26)