I saw this yesterday. It strikes me that the simplest way to do this is to STOP SUBSIDIZING PEOPLE WHO CAN'T SUPPORT THEMSELVES! For the last half century the giant welfare states around the world have been ensuring that billions of people who cannot or choose not to support themselves have food, shelter, health care and education. Capitalism and free markets are an excellent way to control population if you stop promising people that they will be taken care of no matter what. If people have to provide for themselves and their families and if they know the government is not going to give them more money each time they have a baby there will be fewer babies. Better yet, this puts the decision back on the individual. If you want to have 19 kids like the Duggars that is your decision as long as you can pay for them.
Another thing, stop sending aid to support people in foreign countries. First of all it is not going to poor people for the most part, second it prevents industry from developing in those countries, third it supports populations that are larger than what can be sustained given the local resources and abilities of the society.
The current policy of socialist governments around the world seems to be this:
1. Ensure no one starves or does without due to their own laziness, incompetence or stupidity.
2. When these natural barriers to population growth are removed, put in artificial ones.
The best that can be said about the one child policy is that it is fair. Rich and poor will have the same limit. Of course they won't, rich people will pay a fine, members of congress will be exempt, as usual. If someone is successful, innovative and able to support a large family, shouldn't they have one if they choose? Isn't that good for society in general that success is rewarded and reproduced? My guess is if the policy were implemented it would apply to anyone not in government and 50 years from now we would have a world dominated by politicians and bureaucrats. Not to worry, I don't think this policy will be implemented. It was done in China where constituencies are not that important. The only way it will happen here is if the red states start to out populate the blue states. With the lax immigration policies I don't see this being an issue for politicians to worry about for some time.