This is very much a live topic and, as a matrimonial lawyer for many years, is something that I unfortunately come across the whole time.  The manipulator, for want of a better word, in effect emotionally abuses the child for his or her own gain without thought at all for that child's wellbeing.  At the end of the day, the parties chose together to have a child (usually) and their partner was chosen.  Surely, therefore, they should allow that child to know and have a good and meaningful relationship with both parents?  All too often I feel it is driven by "revenge" tactics or the child being the pawn in the last point of control one parent has over another.  It is about time courts were more robust in dealing with this issue