With great difficulty, in most (not all) cases.
“It used to be a fashion amongst men that when a charge was made some sort of proof was brought forward to establish it, and if no proof was found to exist, the charge was dropped.” – Abraham Lincoln
Few courts are slaves to such fashion when it comes to allegations of child abuse (and parental alienation is a form of child abuse; even if the term “parental alienation” is not codified, manipulating a child to fear and hate a parent is emotionally and psychologically abusive in anyone’s book).
Many courts treat evidence differently when dealing with matters of child custody. It’s as though they feel, when it comes to matters involving children, that the preponderance of evidence standard is not good enough, not “safe” enough. If an allegation of child neglect or abuse is made, many courts get scared. Not necessarily scared for the health and safety of the child, however, but for the safety of their own careers. This article on domestic violence restraining and protective orders (click here to access it) explains the problem and its adverse consequences. In a nutshell, many judges and other judicial officers analyze claims of child abuse this way: “If I make findings and enter orders that treat the accused parent as abusive, then nobody can fault me for ‘failing to protect the child,’ (‘better safe than sorry’), but if I don’t (because I find that the accusing parent failed to meet his/her burden of proof) and then later the accused parent is caught committing child abuse or new evidence comes to light proving he/she was abusive in the past, then I look like I wasn’t paying close enough attention, that I am incompetent or worse, that I did not care about child safety and welfare. Better to nip that problem (for me) in the bud and just err on the side of caution.”
Can you see the damage done when judges think and act this way? “Protecting” a child from a parent who has done no harm results in three victims: 1) the innocent parent 2) the innocent child whose relationship with that parent is now seriously damaged, if not destroyed, and 3) the child’s, the parent’s, and the public trust in the judiciary and faith in the impartial administration of justice. What kind of respect for law and order are parents and children who were victimized by a self-serving, cowardly judge going to have? James Madison put it perfectly:
We are to look upon it as more beneficial, that many guilty persons should escape unpunished, than one innocent person should suffer. The reason is, because it’s of more importance to community, that innocence should be protected, than it is, that guilt should be punished; for guilt and crimes are so frequent in the world, that all of them cannot be punished; and many times they happen in such a manner, that it is not of much consequence to the public, whether they are punished or not. But when innocence itself, is brought to the bar and condemned, especially to die, the subject will exclaim, it is immaterial to me, whether I behave well or ill; for virtue itself, is no security. And if such a sentiment as this, should take place in the mind of the subject, there would be an end to all security what so ever.
Utah Family Law, LC | divorceutah.com | 801-466-9277
(4) Eric Johnson’s answer to How does one prove false allegations of parental alienation? – Quora