Arbitrator Disclosure In 2026: Three Rules That Still Catch Arbitrators Off Guard

Arbitrator Disclosure in 2026: Three Rules That Still Catch Arbitrators Off Guard

Awards worth hundreds of millions of euros have been annulled in recent years. Not because the underlying arbitration was procedurally flawed. Not because the tribunal got the law wrong. Because an arbitrator failed to disclose something a party was entitled to know.

The duty to disclose is not controversial. Every major set of institutional rules acknowledges it. The IBA Guidelines codify it. Arbitrators understand it exists. And yet disclosure failures remain among the most common — and most costly — causes of challenge proceedings and set-asides.

The problem is not ignorance of the rule. It is a persistent misjudgement of its scope. Here is where that misjudgement most often occurs — and what to do about it.