All these meetings reported in the New Testament were assemblies of the local church attended only in Acts 15 by representatives from other places. [Herman Bavinck, Reformed Dogmatics, 4:431]
The apostles and the elders were gathered together to consider this matter. ... And all the assembly fell silent, and they listened to Barnabas and Paul as they related what signs and wonders God had done through them among the Gentiles. ... Then it seemed good to the apostles and the elders, with the whole church, to choose men from among them and send them to Antioch with Paul and Barnabas. ... (Acts 15:6, 12, 22a)
Herman Bavinck's Reformed Dogmatics is a erudite piece of Reformed scholarship. Yet, surprisingly, in this particular section there is a denial that Acts 15 depicts a broader church assembly. Rather, according to Bavinck, Acts 15 depicts an assembly of a local church with "representatives from other places."
From the surface, there is already a problem with the idea that Acts 15 depicts a "local church gathering." While we are not given the number of believers in Jerusalem, we do know that there were three thousand baptized at Pentecost, and with growth, we can assume that the church in Jerusalem probably numbered in the thousands and the tens of thousands. Even after the great persecution in Acts 8:1, the church would have bounced back in the many years since. With this number of believers, it is unlikely, given the hostile climate in Jerusalem, that thousands of Christians would be worshiping in public as one assembly, much less deliberate doctrinal issues. Therefore, the Church in Jersualem likely was made up of multiple local churches, all of them under the authority of the Apostles, and the elders and deacons tasked to help them. The assembly in Acts 15 would thus likely be the meeting of the leaders of the Jerusalem churches, with representatives from the other churches.
The next problem with the idea that Acts 15 is an assembly of the local church is that the issue under discussion was an issue in the churches of Antioch, caused by Judaizers that come from Judea. If this was a local church assembly, why would it render a ruling that goes out to the other churches in Antioch, Syria and Cilicia? If we grant that these Judaizers came from the Jerusalem churches, the ruling would be to discipline the Judaizers as teaching contrary to what the Jerusalem churches believe in, not to give a positive command that is obligatory on believers not in the "local church" of Jerusalem. A "local church assembly" would disavow the Judaizers as teaching contrary to what the Jerusalem churches teach, while letting the "local church" assemblies in Antioch and other cities settle the doctrinal issue for themselves in their own "local church assemblies." After all, each "local church" is autonomous, or is it not?
Acts 15 therefore must be an example, the only canonical example, of a broader church assembly. It is the "whole church" of Jerusalem inasmuch as all its representatives were there, thus verse 22 is not giving us the impression that every single member in the churches of Jerusalem head for head were present in this gathering and they all made that decision, but that the vote to send men to Antioch with Paul and Barnabas was unanimous from all the representatives from all local churches. Contra Bavinck, Acts 15 functions as an example of a broader church assembly, and a basis for Presbyterian church polity.