Talmud do Sanhedryn 2:13

There¹⁰⁰In Babylonia (Babli 174a in the name of R. Joḥanan.), they instruct that practice everywhere follows Rabban Simeon ben Gamliel except for the guarantor¹⁰¹The Mishnah here, Bava batra10:14., Sidon¹⁰²Mishnah Giṭṭin 5:5., and the last proof¹⁰³Mishnah Sanhedrin 3:13 (in most Mishnah editions, the last statement of Rabban Simeon in Mishnah 3:8 dealing with the right of the parties to submit proof to the court out of order.). They say, only in the Mishnah¹⁰⁴But not in the baraitot. The Babli agrees, loc. cit.. Rebbi Immi bar Qorḥa in the name of Rav: Why did they say, practice everywhere follows Rabban Simeon ben Gamliel? For he pronounced specific practices decided by his court¹⁰⁵His pronuncements have the status of precedents decided by the Supreme Court..