‘And the whole company of them rose up, and brought him before Pilate.'
The Sanhedrin as a whole then brought Him to Pilate. ‘Whole company' is probably not to be taken literally. It may not have included dissenters, and Pilate would certainly not have been happy to see them all at once. Luke's point is rather to involve ‘the whole Sanhedrin' as a group (although in Luke 23:51 he mentions at least one member who did not agree with the verdict. There may well have been others). All were responsible for Him being brought to Pilate.
The chief priests remembered how He had hit at the Temple revenues by casting the traders from it, were angry at what they had heard of His suggestions that the Temple would be destroyed, and possibly feared that He might disturb the equilibrium with the Romans which was so much to their advantage (John 11:48-50). The Scribes and Pharisees were bitter because He showed up their teaching and refused to side with them and accept their complete authority on religious matters. The rich laymen were probably concerned lest anything be done that might disturb the maintenance of the status quo, securing their wealth and position. They would not feel that they could get involved in religious matters when the recognised religious experts, the ‘scholars', were all seemingly against Jesus. Thus all for their own reasons were agreed that it was a good idea that He should be got rid of.