So, who enforces the borders? Each sovereign nation would be responsible for their own compliance within their borders, though cross-national boundary coordination would be very helpful. Some nations might not have the resources, or the will, to enforce preserve borders, they might seek assistance from other nations, or they might openly reject the 50/50 idea and continue to develop up to 100% of their lands. Even if the 50/50 preservation is only enforced on the high seas, it will be a huge step forward from conservation efforts today. Nations reaping the rewards of 50/50 conservation should serve as models for others, examples of the benefits. The main problems I would predict are in the conservation of energy resources, and in differential conservation between competing nations, with those who do more conservation feeling somehow unfairly disadvantaged versus those who do less.