At midnight on the night of 1 to 2 May 2000, at 04:00 UTC, and by direction of President Clinton, the United States Department of Defense stopped operating Selective Availability. Selective Availability was the deliberate, dithering error the American military had built into the civilian GPS signal to keep it from being accurate enough to guide a weapon. With it switched off, the position error available to an ordinary civilian receiver fell overnight from roughly 100 metres to roughly 10 metres. Nothing changed in the sky. The satellites were the same, the receivers were the same. A single decision in Washington made the same signal ten times more useful to everyone on the planet at the same instant.
The economic consequences were enormous and largely unforeseen in their scale. Ten-metre civilian accuracy was the precondition for turn-by-turn car navigation, for the location services that later became standard in every smartphone, for precision agriculture in which tractors steer themselves to within a row width, for surveying, logistics, ride-hailing and a long list of businesses that either did not exist in 2000 or existed only as expensive niche products. The decision is often cited as one of the highest-return acts of government deregulation in history, because it created vast private value at essentially no ongoing cost to the state that made it.
The formal justification was partly technical and partly commercial. By 2000, techniques such as differential GPS were already letting sophisticated civilian users correct out much of the Selective Availability error, so the military value of the degradation was eroding while the economic cost of holding it in place was rising. The Clinton administration reasoned that the United States would gain more from a thriving civilian GPS market, dominated by American firms, than it would lose by giving up a form of degradation that determined adversaries could increasingly defeat anyway. There was also confidence that the military could, if it needed to, deny GPS regionally through newer localised jamming and denial methods rather than through a blunt global switch.
The context of the decision is easy to forget now that ten-metre accuracy feels like a law of nature. In 2000 the internet was young, the smartphone did not exist, and satellite navigation for ordinary people meant expensive standalone units that few owned. The commercial promise of accurate positioning was mostly potential rather than realised, and much of that potential was invisible to policymakers. What Clinton's decision did was remove an artificial ceiling and let a market discover uses that no one in government had fully imagined. The scale of what followed, from billions of location-aware phones to autonomous farm machinery, was a consequence rather than a plan. That is part of why the episode is instructive. A single administrative act, reversible in principle, seeded an entire category of global economic activity, which meant that same category inherited the reversibility.
That last point is the one worth dwelling on. Turning off Selective Availability did not surrender control. It changed the form of control. The United States retained, and retains, the ability to degrade or deny the civilian signal, whether globally or over a chosen theatre, and it retained sole authority over the satellites, the ground control segment and the operating policy. What the world received in May 2000 was a better signal, not a share of ownership. The button that had been pressed since the system's early operation was simply released, by the same hand, on the same panel, and that hand kept the button.
Subsequent United States policy has committed not to re-enable Selective Availability, and later generations of GPS satellites were built without the capability to broadcast the degraded signal at all. That is a genuine and durable commitment. But it is a commitment of policy and hardware design made by one government about its own system, and the underlying principle is unchanged. The most widely relied-upon positioning, navigation and timing signal on Earth is operated by a single sovereign, which sets the terms of access unilaterally and can change those terms, in one direction or another, whenever it judges its interests require it.
For other states the episode carried a double message. On one hand, the generosity was real and the benefits flowed to everyone. On the other, the speed and unilateralism of the switch showed exactly how much discretion sat in one capital. A world could be running its economy on ten-metre accuracy one day because Washington decided to allow it. The same structure that granted the improvement could, in principle, reverse it. That is precisely why the European Union pressed ahead with Galileo, and why every other major power built or bought into an alternative. Selective Availability being switched off was a gift. It was also a demonstration of who owned the switch.