Quinn Emanuel Urquhart & Sullivan has defeated a High Court summary judgment and strikeout application brought by the Republic of Argentina in a bondholder dispute for €645 million plus interest.

The claim relates to euro-denominated securities issued between 2005 and 2010 that came with yearly payments linked to gross domestic product growth. Claimants including Palladian Partners argue that the South American country breached its contract in 2014 by rebasing its GDP calculations to 2004 prices from 1993 prices.

That rebasing, the bondholders say, requires adjustments to the securities.

Argentina asked to dismiss the case, saying that contractual documentation prohibited claims against it unless the claimants can show bad faith, willful misconduct or manifest error.

The bondholder win comes as Argentina inches closer to a deal with creditors to restructure $65 billion in debt. The struggling economy defaulted on those obligations in May.

Three major creditor groups came together Monday to unveil a joint counteroffer, lowering their demands but toughening opposition to a "final" offer the government made in early July.

Quinn Emanuel partner Aidan O'Rourke led the team representing claimants in the High Court case, alongside Sue Prevezer of Brick Court Chambers and Alex Barden of Fountain Court Chambers.

The claimants said through Quinn Emanuel that the judgment is "an endorsement" of the claimants' arguments—namely that Argentina has acted in breach of contract by failing to apply the terms of the securities.

Sullivan & Cromwell represented Argentina in the case, with Reed Smith appearing on behalf of the trustee.