Multiplex, which blamed its former subcontractor Cleveland Bridge for the delays which have bedevilled development of the new £757 million, 90,000-seat national stadium, is seeking up to £45 million from Cleveland.
Darlington-based Cleveland, which built the stadium's iconic steel arch but walked off the site in August 2004 citing breach of contract, counter-claimed for £22.6 million.
At the centre of the lawsuit is a 2004 agreement in which the two sides attempted to resolve a series of disputes concerning cost overruns by re-evaluating Cleveland's work.
Mr Justice Jackson, in the Technology and Construction Court in London, ruled on a complex dispute in which each side accuses the other of 'repudiatory' breach of contract.
This is a breach so fundamental the aggrieved party may treat the contract as terminated and sue for damages.
While there were a series of mixed rulings the key decision - over the 'repudiatory breach' - went with Multiplex.
The judge said that 'while ruthless', Multiplex's actions had been 'lawful'.
Delays in completion of the vast Wembley complex have resulted in major sporting events, such as the 2006 FA Cup final, being moved to other venues.