JUDGMENT

Lord Goff of Chieveley J:

There is before their Lordships an appeal by the appellants, Societe Nationale Industrielle Aerospatiale (whom their Lordships will refer to as "SNIAS", from a judgment of the Court of Appeal of Brunei Darussalam delivered on March 20, 1987, in which the Court of Appeal dismissed an appeal from a decision of Mr. Commissioner Rhind (delivered orally on December 22, 1986, and in writing on January 16, 1987) declining to grant an injunction restraining the respondents from continuing proceedings commenced by them in the 61st Judicial District Court of Harris County, Texas.

The matter has arisen as follows. On December 16, 1980, a Puma 330J helicopter crashed near Kuala Belait in Brunei. There were 12 people on board: all were killed. Among those killed was Yong Joon San.

Yong Joon San was a very successful businessman. His home was in Brunei, where he lived with his wife and children. His main business (carried on by him under the name of Yong Joon San General Contractor) with a business in his sole proprietorship concerned with providing catering services to oil rigs and other structures operating off Brunei. He also had a much smaller business in Malaysia called Yong & Company, which was likewise in his sole proprietorship. It appears from the evidence presently available that Yong Joon San was making a very substantial income from his business activities, and especially from his catering business in Brunei; and that in addition he was making substantial sums on the New York Stock Exchange. One estimate given of his income in the year before his death was over US$1,800,000. It has also been stated that, by the time of his death, he had accumulated a fortune in the region of US$20,000,000.

The Puma helicopter which crashed was manufactured by SNIAS in France in 1978. SNIAS is a French company in the ownership of the French state. The helicopter in question was owned by an English company, British and Commonwealth Shipping Company (Aviation) Ltd. ("British and Commonwealth"); but it was at all material times operated and serviced by Bristow Helicopters Malaysia Sdn. Bhd. ("Bristow Malaysia"), an associated company of Bristow Helicopters Ltd. ("Bristow UK"), and was under contract to Sarawak Shell Bhd. and so was based at Miri Airport in Sarawak. The Bristow companies are ultimately owned by British and Commonwealth.

The Brunei Government ordered an inquiry into the accident. The inquiry was conducted by the Brunei Chief Inspector of Accidents, Mr. J.M. Holden. His report was submitted to the Director of Civil Aviation of Brunei on July 20, 1982. The main conclusion of the Report was as follows:

"... the most likely cause of the accident was a planetary gear failure in the second stage of the two stage epicyclic main gear box reduction gear; the associated metal debris caused jamming within the rotating assemblies, generating forces which fractured the common epicyclic ring gear and the main gearbox casing. This resulted in a gross instability in the rotor system which caused blades to strike the fuselage."

It was further concluded that "the initial cause of the accident was due to the mistaken health monitoring of the gearbox leading to a deterioration of the mechanical condition of the gearbox components." (Another possible cause was briefly mentioned, but their Lordships were informed that this is no longer regarded as a serious possibility and it can therefore be disregarded).

The point about "mistaken health monitoring of the gearbox" is explained in the body of the Report. The maintenance practices to be followed in the event of gearbox contamination are set out in the SNIAS Maintenance Manual, which refers to nickel or carbon steel particles taken from the filter and magnetic plug, and lays down a procedure to be followed in the event of over 50mm² of such particles being collected. As is pointed out in the Report, this implies that debris from the filter and magnetic plug should be laid out and m