What is Parental Alienation Syndrome (PAS)?

Approximately  one in two marriages in the United States ends in divorce, affecting about a  million children per year. About 10% of these divorces involve custody litigation. Some children are or become emotionally estranged from one or both parents during this process. The cause of this estrangement cannot be determined without an in depth understanding of the family's history and dynamics. Research has shown that the issues underlying parent attachment or estrangement  are complex and do not lend themselves to easy answers. However, some child custody evaluators rely on simplistic "junk science" theories to explain the child's behavior and recommend "one size fits all" type solutions to force the child to divide their love 50-50 between their parents.
Parental Alienation Syndrome (PAS) is one such theory. This unsophisticated, pseudoscientific theory explains a child's estrangement from one parent or allegations of abuse at the hands of one parent by blaming the other. The theory, developed by the late Richard A. Gardner, M.D., portrays the preferred parent (usually the mother under PAS) as an evil "alienator" who is virtually solely responsible for turning a vulnerable child against their estranged parent (usually the father under PAS).
The simplistic solution is to separate the child from the parent they prefer and place them with the parent they reject or report as having abused them. Despite the fact that many of the assumptions underlying PAS theory have repeatedly been disproven scientifically (see below), Gardner believes that judges should back up PAS-trained therapists' conclusions with the full force of the law and impose fines, permanent loss of custody, and jail terms to parents (mainly mothers) who do not comply.
Although some mental health professionals and child custody evaluators, attorneys, and judges have been quick to accept and admit PAS as evidence in these disputes, there has been no consistent empirical or clinical evidence that PAS is a valid syndrome or that the so called "alienator's" behavior is the actual cause of the alienated child's behavior towards the target parent (Walker et al, 2005). In fact, the majority of mental health and legal experts who have studied the issue consider PAS theory to be both erroneous and dangerous to the children involved.
http://www.leadershipcouncil.org/1/pas/faq.htm