Segmented sovereignty

Whenever someone proposes governing a problem at the scale of the whole planet, the same objection comes back: states will never give up their sovereignty. And mostly that’s true. But not always — and the exceptions are instructive.

The IAEA example

The clearest case is the International Atomic Energy Agency (IAEA). Its inspectors can enter a country’s most sensitive nuclear sites and carry out spot inspections — something states guard jealously almost everywhere else. They didn’t hand over sovereignty in general; they handed over a single, narrow slice of it — control of nuclear materials — to an independent body of technical experts, for the sake of everyone’s survival. Jonathan Blake and Nils Gilman call this segmented sovereignty.

There’s a twist in the story. The IAEA was originally founded to promote atomic energy — to spread cheap power to countries that didn’t have it. What gave it teeth was a crisis: after the world held its breath through the Cuban missile crisis, states signed the Non-Proliferation Treaty, handing the agency real powers to monitor and inspect. The crisis opened a window that calmer times had kept shut.

The pattern

Pull back and a transferable pattern appears. Segmented sovereignty tends to work when there is:

• a narrow, functional scope (nuclear materials — not “most things”),
• technocratic expertise deliberately kept out of day-to-day politics (independent central banks are another example), and
• a shared, existential threat clear enough to override the reflex to guard sovereignty.

It’s not a utopia. The nuclear regime has real power imbalances baked in — the recognised weapons states get to keep what others may not — but for the most part it has worked. To Blake and Gilman, that points to a possibility: if states have ceded a slice of sovereignty before, in the face of a shared threat, they might do it again for a planetary one.

Where governance hasn’t caught up

The flip side is the Outer Space Treaty of 1967, written when only a handful of states could reach space. Today there are roughly 11,000 active satellites and an estimated 170 million pieces of debris, and the primary launchers are private companies, not governments. The treaty’s principles have held up remarkably well, but the institutions to enforce rules at today’s scale — with non-state actors in the mix — simply don’t exist yet. It’s a reminder that segmented sovereignty has to be built, deliberately, before the next crisis rather than after it.

Why it’s here

Segmented sovereignty is a rare, concrete answer to the “but how would that ever happen?” question that haunts planetary governance. It’s also a useful lens at any scale: pooling a specific authority into a trusted, accountable, narrowly-scoped institution is exactly how a commons governs a shared resource without anyone having to surrender everything.

Sources

• The Launch of the Planetary Compendium — Berggruen Institute × Dark Matter Labs (2025): youtube.com/watch?v=hhTyUhc8Rm8. The IAEA case study is by Jonathan Blake & Nils Gilman.
• Jonathan S. Blake & Nils Gilman, Children of a Modest Star: Planetary Thinking for an Age of Crises (Stanford University Press, 2024).