Ross Brawn insisted his team are innovators rather than cheats as he endured a grilling in the diffuser row hearing.

Brawn was pointedly described as "a person of supreme arrogance" as Formula One's newest team boss came under fire at one stage during the International Court of Appeal hearing in Paris.

But the Brawn GP head stood his ground as personal slurs and the weight of the FIA regulations were thrown at him at motor sport's headquarters overlooking the Place de la Concorde.

FIA technical director Charlie Whiting was also forced to endure a 75-minute cross examination as he and the organisation were accused of "getting it wrong, and not understanding the point".

The brickbats were hurled during a marathon sitting that lasted over eight hours as Ferrari, Renault, Red Bull and BMW Sauber squared up to Brawn GP, Toyota and Williams in front of five ICA judges.

At the heart of the matter is the conceptual design of the diffuser - an aerodynamic body part that aids performance - towards the rear of the cars belonging to the three teams in the firing line.

Central to a 'double-decker' design are two apertures that assist airflow, so increasing downforce, which in turn results in greater speed.

Reference was made to the fact that it was a new approach, and therefore had to be ratified by the FIA before being applied to the car.

But a defiant Brawn said: "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."

On a more personal level, Brawn was twice asked to retract remarks made in his personal submissions in which he criticised Rory Byrne and Adrian Newey.

Byrne is Ferrari's former chief designer, a long-standing colleague of Brawn as they won five drivers' and six constructors' titles together earlier this decade, and who now works as a consultant to the Maranello-based team.

Brawn had claimed the appellants' case was "a vindictive response... that amounted to a fishing expedition".

Asked to withdraw his comment as it was claimed it served as a slight against Byrne, Brawn said: "I have the highest regard for Mr Byrne.

"But we are on opposite sides in this argument, so I stand by my statements."

In his written submission, Brawn also accused Red Bull's technical guru Newey of "being unethical and of bringing the sport into disrespute".

Newey had perhaps naively claimed in his own statement that the speed of the Brawn GP car that has this season won both races in Australia and Malaysia with Jenson Button at the helm was a safety concern.

But Brawn rebutted: "The safety implication relating to a technical feature of the car is a bit below the belt."

Again when asked to renounce his words, Brawn replied: "No."

Leading the debate was Ferrari's legal representative Nigel Tozzi QC, who successfully argued the team's case over 'spygate' and at last year's inquest into Lewis Hamilton's chicane-cutting move at the Belgian Grand Prix.

At one stage, Tozzi noted of Brawn that "only a person of supreme arrogance would think he is right when so many of his esteemed colleagues would disagree".

Tozzi, aside from trying to stoke up Brawn, also attempted to tie Whiting up in knots with regard to the regulations.

He argued that "the position of the FIA is totally baffling...we urge you to save the FIA from itself".

However, it could be argued Tozzi baffled the judges - one of whom, Malta's Guido de Marco, occasionally nodded off - with his lengthy inquests into the wording of the rules and what constitutes a hole.

As Paul Harris, representing Brawn GP, noted: "What we have seen is a sideshow, irrelevancies, or to coin an English phrase, a red herring."

The tables were seemingly turned, though, when Brawn made reference to a number of cars - including Ferraris - from recent years that included various slits in other parts of the bodywork which could be construed as contrary to the regulations.

It was a point referred to by Byrne, effectively meaning that every title-winning car stretching back to the early 1990s could be deemed illegal.

As Williams CEO Adam Parr remarked: "I find it almost pleasurable to hear Ferrari say they have won 11 world championships (drivers' and constructors') with an illegal car."

Tozzi attempted to downplay the positive perception of Brawn as an innovator by throwing back a remark employed recently by FIA president Max Mosley.

"It was he who said recently that costs must be reduced by limiting the opportunities for technical innovation," said Tozzi.

"If the appeal is dismissed then the claims by the FIA they want to make the sport more attractive and reduce costs will sound hollow."

The judges will now deliberate on a ruling made by the stewards at the Australian Grand Prix that the Brawn GP, Toyota and Williams cars are indeed legal.

A verdict is due tomorrow, although their full findings are not due to be revealed until either later this week or early next.

At stake are the race results in Melbourne and Sepang as the judges have the power to overturn them, although such an eventuality is not expected.