Aircraft lessors have won a court battle over war risks cover after planes worth more than $US4 billion ($6.1 billion) were stranded in Russia following the invasion of Ukraine.

The British High Court decision, handed down by Justice Christopher Butcher last Wednesday, involved six actions in a 12-week “mega trial”.

Law firm Herbert Smith Freehills Kramer says it secured a $US1.035 billion ($1.6 billion) win for client AerCap – the world’s largest aviation lessor and the lead claimant given the size of its exposure.

Sanctions imposed after the 2022 invasion of Ukraine prohibited leasing aircraft to Russia, but companies seeking the return of planes already there were largely unsuccessful.

The AerCap claim involved the loss of 116 aircraft and 23 engines leased to Russian airlines.

Law firm Clifford Chance, which represented three lessors, says the ruling is likely to have global ramifications, with similar proceedings under way in Ireland, the US and elsewhere, and it sets a precedent for political risk insureds amid rising geopolitical uncertainty.

“[Russian President Vladimir] Putin’s invasion of Ukraine and subsequent restraint of over 400 commercial aircraft was the paradigm scenario the owners thought they had insured against,” partner Julian Acratopulo said. 

“The ruling underscores the integrity and reliability of the UK courts in upholding contractual commitments, even when faced by multiple defendants with significant combined resources and the most complex circumstances imaginable.” 

Law firm Wikborg Rein – which represented insurers defending claims brought by three lessors under hull all-risks cover – says the court has ruled in favour of those underwriters by finding it was the war risks policies that responded. 

“The judge considered that the sole proximate cause of the loss was the passing of legislation by the Russian government which prohibited the export of the aircraft from March 10 2022,” the firm said.  

“Accordingly, the lessors’ claims against all-risks insurers have been dismissed in their entirety in the judgment handed down.” 

Insurers involved in the legal disputes included AIG, Chubb, Lloyd’s and Swiss Re. 

The decision is available here.