Habitat Population Control

Hi Guys,

I realize there has been an awful lot of fur flying over Eugenics (which really does mean: "The study of hereditary improvement of the human race by controlled selective breeding" - I looked it up) lately, and I have seen the proposition advanced that unrestricted and unlimited breeding is a basic human right. With all due respect, I must point out that this is impractical. Given the following three Axioms (they may not, in fact, be axiomatic; but they did seem reasonable places to start my reasoning from):

The resources available within a single habitat are finite (by which, I mean the living space, food, fresh water, air, and other life support consumables - certainly another habitat may always be built... but please see my caveat 'within a single habitat'. Habitats are expensive, and not necessarily trivial to produce, nor free to colonization by any who wander up wanting space.)

The technology available for creating new resources, or producing existing resources more efficiently, are finite within reasonable time scales (by which I mean, a miracle hydroponic technique which will produce ten times as much food three years from now doesn't help with today's factor of ten shortfall; a problem in the near term must be solved with only the resources available in the near term)

And finally, (and this IS an actual, honest to goodness (tm) Axiom) that any free breeding population will expand to exceed its available resources (basic driving force behind natural selection, that. I may have been sloppy in my phraseology though.)

It seems reasonable to conclude that population control will be a vitally important issue in any habitat, especially when the limits of the life support system are being reached. So, what measures would be rational, with regards to limiting the population? Can it be done without continuous governmental intrusion? Would any such measures be Eugenics? How could abuses be discouraged? What about people who defy the policy, and their children?
I don't mean to start up the whole Fascist Blood-slinging feud again, but it has surprised me that nobody has approached the issue of breeding from the rather obvious (and I hope relevant) angle of population control and life support stresses. In the past, this issue has been hand-waved away under the presumption that 'Oh, the people living there will sort it all out, I guess'; but eventually we may run into the limits which constrain us here on Terra....
Just my two cents - anyone else have a take on this?