Overpopulation: You get to cast the deciding vote.

[Regina]

I think forced sterilization is probably a step too far, however I would instead support taxing people with 2 children, and very heavily taxing people who have more than 2. This would have to apply only to people who do not have children yet, not to families which are already large, as it's not fair to suddenly slap that tax on them out of nowhere. That's more favourable in my opinion than forcibly sterilizing people. You can technically have as many children as you want, but it's strongly discouraged and tax is used as an incentive not to have more than 2.

That's how I'd do it. Sure it's still a bit unethical, but I don't think you can ever introduce population reduction without at least some unethical stuff. It's certainly more favourable than outright killing off living people or sterilization.