What you call "force of law" is just rules decided by everybody for the good of all, in a democracy. You use this expression to make it look like oppression, but it is the complete contrary, it is mutual help by choosing beneficial rules.
Helping to build democracies, you help everybody! Except the few dictators, but why would you care for their feelings more than the feelings of the whole population. Unless they are happy being enslaved, in which case I'd say that it is already a democracy, because things are like they wish they'd be! But this is delusional.
Planet-wide rules are necessary because the world is finite and connected, that's as simple as that.
You impoverish the neighbor countries for the sake or the nation's wealth, and next thing you know there is war at your border. Or your supplier is from a country in crisis and suddenly you can't work anymore. Or your exported all of your CO2 emissions so that you don't produce it directly, but now all your country's forests are on fire because of the warming from emissions you made happen on other places on Earth...
But this idea of world democracy is not at all incompatible with locally applied specific rules too. It even already exists in modern democracies: for specific issues you decide local solutions, with the benefit of the larger scale government being that it is guaranteed to not jeopardize the greater good of the whole (in the case at hand, the planet! it is always a good thing not to jeopardize the planet!).
Without the existence of such planet-scale government, you end up with local agents (countries) who take decisions seemingly in their benefit but actually with consequences putting the planet and everybody in danger (harmful instantly for some people outside their country, and harmful for themselves too on a time scale greater than their next election -- this problem is solved by considering the impact of all decisions on all points of the planet, thus my idea).