The paper explores the broadening of the tax immunity in article 150, incise VI, letter “d” of the brazilian Federal Constitution with a view to protect e-readers. Through study of the constitutional history of the norm, it elaborates a definition for tax immunity for the purpose of interpretation. The paper defends using a three-part hermeneutic method to get the essence of the immunizing rule, targeted to the guarantee of access to culture and knowledge. It develops a doctrinal and judicial analysis of the immunity towards popular e-readers, with the purpose of determining characteristics of inclusion in the constitutional rule. In the end, the paper proposes the use of preponderance as a means to evaluate how close or distant these devices are in the eyes of the concepts brought by the Constitution.