I intend in this paper to offer some reflections on the problem of subjectivity in the writing assessment, in the examinations for access to the University and other public competitions in Brazil, and to demonstrate the unfeasibility of keeping such type of test, given the impossibility of doing justice to the candidates. I present a brief history of assessment over time, a succinct bibliographical summary on the subject and some data on the state of the art in Brazil. I analyze the system of writing assessment of the ENEM, showing its insustainability. I support myself, theoretically, in Bakhtin and specialists in assessment and evaluation. I present, also, a small empirical research on the system of writing evaluation of the ENEM.