I have worked in the family law system for quite some time now and I really think the fundamental problem is that people think the law can deal with what are really emotional/psychological problems.
And I think it is a very blunt tool for that kind of work.
there are parents, both mothers and fathers, who can't see beyond their own emotional pain and/or need to control. in the aftermath of a breakup they use the children to hurt the other parent. Its awful and it causes so much long term damage to the children. But if a parent doesn't have the insight to understand that, I don't see how imprisonment is going to magically make them understand. They will just see themselves as innocent persecuted victims.
Frankly, if one parent is buggering about re contact for no good reason, I think the only real solution is to change the child's residence. The problems arise when the other parent just isn't able to offer the child a home.
I don't have the answer. I just know that this is not a situation that is ever going to improve by simply locking people up.