‘And it came about on the next day, that their rulers and elders and scribes were gathered together in Jerusalem; and Annas the high priest was there, and Caiaphas, and John, and Alexander, and as many as were of the close relatives of the high priest.'
The next day a meeting of the Sanhedrin, the highest Jewish authority and court, was called, made up of around seventy men taken from among the rulers (chief priests), the elders (important lay persons) and the Scribes (mainly but not entirely teachers of the Pharisees). They included a number of close relatives of the High Priests. Annas was High Priest according to Jewish Law, but he had been replaced as High Priest by Caiaphas under Roman Law. Many of the people thus still considered Annas to be the true High Priest. Along with them were John, possibly the Jonathan who succeeded Caiaphas, and Alexander, of whom we know nothing. Both were no doubt close relatives of the High Priests. In fact Annas was probably still deliberately and defiantly called ‘Annas the High Priest' by the people, and Luke may simply here be citing this popular designation. Luke is not suggesting that Caiaphas was not the High Priest as well. (According to the Jews once a person was High Priest he was High Priest until death. Even a substitutionary High Priest who had to stand in if the High Priest was prevented for some reason from conducting the Day of Atonement ritual, was seen as High Priest from then on, even if he never officiated again. Anyone therefore who had conducted the Day of Atonement was necessarily High Priest).
We may gather from Luke's description that he was not over-impressed with the fairness of the situation. The Sanhedrin was overloaded with the men in whose name the charges had been brought.
‘In Jerusalem.' The point is that the Jerusalem that was to be the launching pad for the Gospel (Acts 1:8) was also the Jerusalem where these men met to impede its progress. There was opposition at the very heart of the place from which the word of God was to go out to the world (Isaiah 2:4).