Where did Saul of Tarsus get the authority to arrest Christians in Damascus?

The Sanhedrin was the religious court in Jerusalem that was required to comply with the laws of Rome. Jerusalem was in the Roman province of Judea. Damascus, hundreds of miles away, was in the seperate Roman province of Syria with its own governor. Roman law ruled in the province of Syria just like it did in the province of Judea and every other Roman province. Roman law was fairly tolerant of different religions, (there was no persecution of Christians at that time) and would surely look down on anyone coming from a different province, armed only with doents from a religious Judeian court that had no juristiction in Syria. Why did Saul think he was going to get away with breaking Roman law by essetially kidnaping people in Syria and dragging them back to Jerusalem? Or did he just make it all up?