I would submit that what you are calling the law of the ancestors is actually the Torah.
The Book of Acts chapter 22
“Brothers and fathers! Listen to me as I make my defense before you now!” 2 When they heard him speaking to them in Hebrew, they settled down more; so he continued: 3 “I am a Jew, born in Tarsus of Cilicia, but brought up in this city and trained at the feet of Gamli’el in every detail of the
Torah of our forefathers. I was a zealot for God, as all of you are today. 4 I persecuted to death the followers of this Way, arresting both men and women and throwing them in prison. 5 The
cohen hagadol and the whole
Sanhedrin can also testify to this. Indeed, after receiving letters from them to their colleagues in Dammesek, I was on my way there in order to arrest the ones in that city too and bring them back to Yerushalayim for punishment.
cohen hagadol = high priest