In modern societies, people decide to marry, more frequently, based on affective choices. In Brazil, during the last decade, there was a 20% increase in marital unions dissolutions. Some spouses fail to overcome the problems and difficulties that arise at the end of a relationship, with their children being the ones affected by their parents’ actions and behavior, thus giving place, in some cases, to the Parental Alienation Syndrome, which is observed in certain disputes that reach Family Courts. This article focuses on the Forensic Psychiatry role regarding the claims and demands that arise from marital dissolution, the Parental Alienation Syndrome and the legislation related to this syndrome, in particular the Brazilian Law 12.318, issued on August 26th, 2010.