In the UK decision of Aioi Nissay Dowa Insurance Company Ltd v Heraldglen Ltd  EWHC 154 (Comm), it was held that the ‘September 11' terrorist attacks on the twin towers of the World Trade Center were two separate events for the purpose of an aggregation clause in a reinsurance contract. The policy provided coverage for “each and every loss”, which was understood to mean “each and every loss or accident or occurrence or series thereof arising out of one event”.
This outcome may be somewhat suprising as both attacks were the result of the same conspiracy, executed within a specific timeframe at a specific location. However, the Court affirmed the decision of a tribunal of arbitrators in finding that, when the doctrine of “unities” was applied, the hijacking of each of the two planes was not sufficiently unified to be considered a single occurrence or two occurrences arising out of one event. Indeed, if only one of the hijackings had succeeded, only one tower would have been destroyed. This case highlights the importance of policy drafting and the scrutiny that will be given to the construction and interpretation of aggregation clauses.