The Portuguese Mental Health Law is complex, aiming to ensure patients liberties and basic civil rights are respected. A specific part of this law regards the compulsory internment and its criteria, being as protective as possible, in order to prevent wrongful internments for people against their will.

The aim of this study is to analyze the mechanisms available to ensure liberty, in a law apparently about coercion.

The methods used consisted in analyzing the law and interpreting its most important details, mentioning them so they can be read and used as examples.

It can be concluded that the Portuguese law has a very strict list of mandatory criteria for the possibility of the compulsory internment, as a way of ensuring no people suffer it wrongfully. The most important being that no person can be interned compulsory if not considered to suffer from a severe mental disease, not being that enough and having to at least present risk for themselves or others, or to juridical goods of high value. Thus, revaluation of the patient is mandatory only five days after the internment by two different doctors, being the same process assured from then on every two months. Only possible flaw lays on the fact that there is no maximum amount of time predicted for internment, being that always dependent of the revaluations made. Although, the law is considered to be good and prevent abusive use of the compulsory internments.