The FIA International Court of Appeal has ruled that the diffusers used by the Brawn GP, Toyota and Williams teams in the opening two races of the Formula One season is legal.

The double-decker system employed by the teams had led to controversy in both Australia and Malaysia after rival teams claimed it gave the 'diffuser three' an unfair advantage on track.

Appeals were lodged by rivals in both Melbourne and at Sepang, which were rejected by race stewards, leading to Ferrari, Red Bull and Renault appealing to the FIA over the matter. BMW Sauber and McLaren were also present at the hearing.

After a hearing of the Court of Appeal yesterday [Tuesday] in which teams had the chance to put forward their evidence, overnight deliberations were followed by a short statement from the governing body confirming that the diffuser system is within the rules.

It means that the top four in the championship standings - Jenson Button, Rubens Barrichello, Jarno Trulli and Timo Glock - will not face the prospect of losing the points secured so far, while the remaining seven teams on the grid now face the prospect of redesigning their diffusers to match the system employed by Brawn, Toyota and Williams.

Renault, for one, are believed to have a prototype version of the system already, which could be used in China this weekend.

"The FIA International Court of Appeal has decided to deny the appeals submitted against decisions numbered 16 to 24 taken by the Panel of the Stewards on 26 March at the 2009 Grand Prix of Australia and counting towards the 2009 FIA Formula One World Championship," a short FIA statement read.

"Based on the arguments heard and evidence before it, the Court has concluded that the Stewards were correct to find that the cars in question comply with the applicable regulations.

"Full reasons for this decision will be provided in due course."