Formula One's governing body dealt champions Renault a blow in their title battle with Ferrari on Wednesday after an appeal court outlawed a controversial damper device used by the team.
The International Automobile Federation's independent court had met in Paris on Tuesday to hear the FIA's appeal against their own race stewards' decision to permit the use of the 'mass damper' system.
"Having heard the explanations of both parties and having examined the various documents and other evidence, the Court quashed (the stewards' decision)," a FIA statement said.
It ruled that the system, which improves race performance by levelling out tyre vibrations and keeping grip levels consistent, was in breach of the technical regulations.
Renault, who lead Ferrari by seven points in the constructors' standings with five races remaining, have used the damper system since September last year and have said it is an integral part of their car's design.
Reports have suggested the Renault R26 car is up to 0.3 seconds slower per lap without the device, which is hidden inside the nose of the car and invisible from the outside.
Several other teams had also developed their own versions of the system.
The FIA ruled last month that it constituted a moveable aerodynamic device and was, therefore, illegal but stewards at the German Grand Prix disagreed after Renault presented technical arguments to them.
Despite been given the go-ahead by the stewards at Hockenheim, the champions did not use the damper in either Germany or the subsequent race in Hungary for fear of eventual disqualification on appeal.
In that time, Ferrari have hacked away at Renault's lead, with Michael Schumacher now 10 points adrift of world champion Fernando Alonso before this weekend's Turkish Grand Prix in Istanbul.
Alonso, winner of six races this year, finished fifth in Germany and retired in Hungary due to a damaged wheel nut while leading the race.
The loss of the device is likely to be most felt by Renault at high-speed Monza in Italy, Ferrari's home race, at Suzuka in Japan and the Brazilian season-ender at Interlagos.
