Brexit will lead to a showdown at the Commercial Court.

The humble sandal is set to take center stage in the first post-Brexit court trade war between the UK and the EU.

The United Kingdom has banned European vessels from fishing for silverfish in North Sea waters to protect wildlife.

But the EU is contesting the move, saying it would discriminate against Danish vessels fishing for sandalfish in violation of a post-Brexit trade deal.

The dispute is headed for a three-day commercial court hearing after formal talks failed to resolve the dispute.

Without a last-minute deal, it would be the first time the two sides have gone to arbitration under the 2021 trade deal agreed by Boris Johnson.

The case is due to be brought before the Permanent Court of Arbitration, which is part of the Dispute Settlement Body in The Hague, before a three-judge panel of international trade arbitrators from Tuesday next week.

They could support the UK’s position – or they could order the UK to change or abandon the ban, in which case Brussels could eventually return tariffs on British exports if ministers refuse to comply.

According to the trade agreement, a final decision must be made by the end of April, although it could be made earlier. There is no right of appeal.

It comes as the UK prepares for tougher negotiations with the EU when arrangements under the trade deal expire in June next year.

Sir Keir Starmer hopes to persuade EU leaders to strike new deals in areas such as security and food trade as part of a wider “reset” with the UK.

Sandel, a group of small eel-like fish species, are collectively managed fish stocks under the trade agreement. It is not reserved for nutritional reasons and cannot be found on restaurant menus in European capitals.

But it is a favorite food of other fish species such as cod and haddock, as well as sea birds such as puffins and kittiwakes.

The UK will stop its own fleet from fishing for the species from 2021 through its licensing regime, which is essential to prevent overfishing and protect the North Sea’s ecosystem.

Rishi Sunak’s Conservative government banned all vessels from catching the species in English waters in March last year, and ministers in the SNP-led Scottish government brought in a similar ban in Scottish waters.

It won praise from the UK’s dialogue groups, which have long campaigned for an outright ban, and Sir Kiir’s Labor government has kept the ban in place since it took power in July.

But it has angered Danish fishermen, who sell sandalwood to animal feed and fish oil producers and have the right to catch the largest EU share of the species in UK waters under a post-Brexit trade deal.

The debate centers on whether or not the UK can restrict fishing rights under EU treaties without requiring the right to restrict passengers for conservation reasons.

In its submission to the court, the EU argued that the geographic scope of the ban was not justified by the scientific model on stock levels or the “economic and social impacts” on Danish fishing communities.

The UK government’s detailed response has yet to be released, but a spokesperson told the BBC it was committed to protecting the environment in line with its trade commitments.

The decision to continue the ban was backed by a coalition of three political parties, conservation groups and staunch Brexiteers.

The renewable energy industry has also expressed interest, arguing that the ban will help the seabird reach the level of “resilience” necessary to build more wind farms while still hitting conservation targets.

The United Kingdom has previously estimated that the sandal caught in its waters is worth around £45 million a year, a small industry in the context of wider trade.

But the debate will be closely watched as how the judges balance the UK’s right to take protectionist measures against economic rights.