If a parent proves him/herself as unfit to have the care of a child, surely they forfeit any parental rights?
I hope you dont mind my responding to your post again because another thought has popped into my head.
I've tried to deal with the central point of children being abused already, so putting that to one side, I'll try to focus again on the disparity between the legal position of the "residential parent", (usually the mother in this country, should I say obviously?), and "non-residential parent".
Our world has progressed you'd have to say in terms of the way different sections of the community are treated, and the word we've all heard so often, and will continue to hear where there remains disparity is "equality", and folks who feel they are not getting equal treatment or rights keep on calling for them to be granted dont they.
It will take too long for me to attempt to go into all the aspects of this, and express my views adequately as to why I'm in favour overall of the situation where mothers get granted custody, (or become the sole resident parent), when the couple split up.
However, you may have read some of my long discussion as to whether there are parental rights in the UK, and I mentioned a number of times the fact that there are "common law parental rights" in the UK, but no statutory parental rights, (the difference being statutory rights are written into law, whilst common law rights refers to the way our courts generally behave, treating residential parents as though they have rights, and not interfering unless there is suspected harm to the child).
My resisting calls for what so many father's groups call "equal parenting" offends a good many of them, but its just my view, and to date in this country it would appear our courts and our government take the same view as I do on this one, (strange I know that I should find myself in the "mainstream" on this topic!).
The last point to make though concerns my oft repeated call for decent parents to be granted statutory rights in this country in the form of a rebuttable presumption in favour of contact. Now you may be surprised to learn that the provision of just those rights was something our government left open the door to when drafting the legislation known here as "The Children's Act 1989". This legislation has been brought in in stages after it was enacted, and though introducing the rebuttable presumption in favour of contact has been considered I believe, it has never been brought in, (for whatever reason).
There we are, you have my arguments more or less completed to consider, and as I think \I've said a number of times the situation in many US states is different, so some of the arguments I'm using wont apply over there, and this may confuse folks somewhat.