Cathy Young has some interesting thoughts on the subject.
The harm done to children by allowing fathers to withhold support is real and not open to debate. I think we can agree on that. In this way the current debate is much different than abortion. In this debate both sides should acknowledge the harm caused by the choice, whereas in the abortion debate the question is what moral status a fetus should have at all.
Men are presumed to get, in general, the right to pay to visit the children born to their lovers or ex-wives.
I like analyzing choice 4 under regulatory takings jurisprudence. Under the Nolan/Dollan cases, there exists a nexus between the taking ($ out of dad's earnings) and the state action (protecting the interest of the child) and, so long as the support award is reasonable, the award will also meet the rough proportionality test.
Child support is about support for the child. End of story. ... If the mother is using the income on herself, it should be reported to the proper authorities, rather than have it cut off completely. Whole government bodies keep track of that stuff in some states.