Psychiatric experts find it is easier to deal with more horrible crimes than highly conflictual divorces. In the former, projections are impossible and “files” raise very interesting issues with regard to criminology; in contrast, in the latter the expert is confronted not just with a family but also and lest one forget, a couple that at one point in time had loved each other. However, the separation resembles a bloodbath. We will not detail the various psychiatric pathologies, which may further complicate a separation: they are well-known and, on a procedural level, do not raise any specific concerns. We will however address “pathological divorces” where although individuals, assessed on a case-by-case basis, are exempt from ascertainable or developing psychiatric pathologies, pathology permeates systemic relations, inextricably linked to hatred or disgust. In this light, fault-based divorces still remain rare: it is in this context, marked by defiance and doubt as to the parental competence of each member of the couple that the psychiatric expert intervenes, with a similar acknowledged mission to that of the court: recommendations to be offered regarding visitation and custody rights. Amongst the conflictual and inextricable situations the most often encountered in expert practice, the parental alienation syndrome (PAS) now known as parental alienation (PA) refers to all psychopathological manifestations observed in children subject to highly conflictual parental separations, and above all, the unjustified or inexplicable rejection of a parent by a child (or even by siblings). This recent entity has raised controversy: some even go so far as to deny the existence itself of this phenomenon claiming that it does not appear in the international classifications of psychiatric disorders. Consequently, it was not included in the last edition of the DSM and does not appear in the ICD classification of the OMS whose 11th edition is currently being prepared. The weaknesses in the scientific concept and its purely passionate dimension, including sexist controversies, must be carefully elucidated in the dismissal or denial of this pathology. The author raises various definitions of parental alienation of which the most recent is undoubtedly the least controversial. He discusses the reasons for the dismissal of the concept by the Scientific Committee of the DSM-5. This dismissal is however quite apparent as although the term “parental alienation” is not contained therein, we will show that the notion is clearly referred to in at least two chapters of the new American classification of mental disorders.