(CNN) -- Jenson Button's opening two wins of the Formula One season will stand after motorsport chiefs ruled on Wednesday that the aerodynamic diffuser fitted to the rear of his Brawn GP car is legal.

Jenson Button's victories in the opening two races of the F1 season were on the line.

The FIA Court of Appeal said that the rear diffusers used by the Brawn, Williams and Toyota teams "comply with the applicable regulations."

The FIA panel sat for eight hours in Paris on Tuesday to hear evidence and their decision backs up the stewards at the season-opening Australian Grand Prix that the controversial aerodynamic devices were within the rules.

Four rival teams, led by Ferrari, had lodged an official appeal against that decision and if had been successful the results in Australia and Malaysia would have been altered to their advantage. Brawn GP chief Ross Brawn had mounted a robust defense of his position.

"We didn't consider this to be a radical new design. It was an innovative approach of an existing idea, and Formula One is all about innovative design. It's a cornerstone and objective of the sport," he told Press Association.

In a statement released after the decision, Brawn added:

"The FIA technical department, the stewards at the Australian and Malaysian Grands Prix and now five judges at the International Court of Appeal have confirmed our belief that our cars have always strictly complied with the 2009 technical regulations.

"The decision of the International Court of Appeal brings this matter to a conclusion and we look forward to continuing on the track the challenge of what has been a very exciting start to the 2009 FIA Formula One World Championship."

The third round of the F1 season takes place in Shanghai this weekend with other teams now having to play catch-up on the all-conquering Brawn.

After a 1-2 in Australia with Button and Rubens Barrichello they lead the constuctors' championship ahead of Toyota. In the title race, Button has 15 points, five more than Barrichello. Toyota pair Jarno Trulli and Timo Glock are next

The Brawn GP team was rescued from the brink of bankruptcy by Brawn and Nick Fry after Honda withdrew from Formula One at the end of 2008 due to the economic downturn.

Button's victory in Melbourne capped a remarkable reversal of fortunes for the team, but the legal wrangling threatened to dampen their celebrations before Wednesday's conclusive ruling.

Ferrari reacted coolly to the decision with team principal Stefano Domenicali sayng they would have to re-design their car.

"Unfortunately this decision forces us to intervene on fundamental areas of the car's design in order to be able to compete on an equal footing with some of the teams," he told the Press Association. "We will now double our efforts to get the team back to the highest level of competitiveness."