Most museum exhibits are beautiful—or at least old.
But an exhibition in 2015 at the World Trade Organisation (WTO) included 60 cardboard boxes of documents.
The point was to give a sense of the scale of two of the body's longest and largest legal disputes,
over American and European subsidies for aircraft manufacturers.
Now the fight is moving out of the paperwork phase. That means tariffs are coming.
On October 2nd the WTO published its decision to allow the Trump administration
to put tariffs on $7.5bn-worth of imports from the European Union.
That is intended to match the harm done to Boeing, an American manufacturer, by the EU's subsidies for Airbus, Boeing's European rival.
It is the largest retaliation the WTO has ever approved.
Senior officials at the United States Trade Representative (USTR) called the victory "historic".
The dispute has been long and bitter.
In October 2004 America complained to the trade body about loans offered by EU governments to Airbus on easy terms.
The following June the EU filed a complaint about the harm to Airbus from subsidies to Boeing,
in the form of tax breaks and generous contracts with the Department of Defence.
Since then there has been enough legal back-and-forth to bore the most ardent plane-spotter.
The WTO ruled against both subsidisers. Each made some adjustments supposed to resolve the other's complaints—but neither was satisfied.
The latest judgment comes as the EU's claim of compliance is still being assessed.
In around eight months, the WTO is likely to authorise the EU to put tariffs on American imports, completing the tit for tat.
In a narrow sense, this is the multilateral rules-based trading system working as intended.
Both parties went through the proper channels to receive an official judgment. Neither took matters into its own hands.
The tariffs America is about to impose on Europe are not unilateral bullying, but an enforcement mechanism of last resort.
They would probably have been applied by any president, even one less tariff- happy than Donald Trump.