In Brazil, the relevance of jurisprudence as a primary source of tax law is evidenced by the legislative changes that have taken place since the creation of the binding dockets from the Supreme Court (dockets of jurisprudence; extracts that summarize decisions from a Court, showing a stare decisis), until the edition of the Civil Procedure Code of 2015 (CPC/15), which contains, generally speaking, binding judicial precedents aiming, above all, the standardization of judicial decision as instrument to give effect to the principle of legal certainty. In this context, despite Brazilian law having roots in Civil Law, its connection with Common Law is identified by adopting the system of precedents in the Civil Procedure Code of 2015. As will be demonstrated throughout this article, however, the system of precedents in Brazil differs substantially from the system adopted by Common Law countries, especially because biding judicial decisions are so qualified from the outset, reaching this status ex lege. The main purpose of this article is to demonstrate that the binding effect attributed by the procedural rules to certain judicial decisions, with regard to tax law, implied a relevant paradigm shift in classical doctrine, which attributed a merely secondary to the jurisprudence to guide the relationship between tax authorities and taxpayer. As a bibliographical methodology, we confronted classical books to specific statutes-as the Brazilian Constitution of 1988-as well as new academic works developed. In addition, we analyzed recent Supreme Courts pronouncements that point to jurisprudence as the primary source of tax law.