This presentation systematizes the academic and methodological discussion of the role of the linguistic expert and expertise in four types: the communicative, the sociolinguistic, the written authorship, and oral authorship expertise, all of which are taken from the Diploma in Expertise in Anthropological Sciences, which I direct, and the National Coordination of Anthropology and the College of Ethnologists and Social Anthropologists A.C periodically organizes. This program of anthropological expertise is part of an ongoing effort of the INAH to “investigate, identify, recover and protect the traditions […] of all the people and social groups of the country” (Organic Law of the INAH, art. 2, II, VII, and X), which involve the respect of human rights (cultural and linguistic), collective, and individual, as well as trying to ensure the right of access to justice which the 2nd constitutional article and the ILO Convention 169 grant.