Why was Jesus tried by Rome instead of the Sanhedrin?

Pilate, being the Prefect of Judea, was the final legal authority in Judea in respect to capital punishment. The Sanhedrin was a decision-making body in respect to local matters. Members of the Sanhedrin, including Caiaphas knew that in order to eliminate Jesus, they had to make him an enemy of Rome; this is why they asked him if he was the Son of God, (a title more-or-less held by Emperor Tiberius Caesar). Jesus responded that he was the Son of God, and in the process put himself above Emperor Tiberius in terms of authority, a seditious act punishable by death. Jesus later confirmed to Pontius Pilate that he was the “King of the Jews” a statement that Pilate did not see as worthy of death in and of itself, however when Pilate saw, that the citizens of Jerusalem were willing to designate Pilate as an enemy of Rome for not punishing Jesus, then he relented and sentenced Jesus to death.