PARIS, France - Mercedes accused Formula 1's governing body of double standards on Thursday at a tribunal that could impose stiff sanctions on the team if it is found guilty of breaking the rules with an in-season tyre test.The team of 2008 World champion Lewis Hamilton - preparing for his home British GP next Sunday - and Germany's Nico Rosberg face anything from a reprimand to exclusion from the championship if found guilty.Lawyer Paul Harris, for Mercedes, suggested the International Automobile Federation had treated his team in a very different way to Ferrari - which faces no action despite both having tested with tyre supplier Pirelli during the 2013 season.FERRARI NOT SUMMONEDMercedes is charged with breaking the rules by using itscurrent car for a 1000km tyre test in Barcelona after that city's 2013 GP with Pirelli in May and thereby gaining an unfair track advantage - an accusation the team denies.Ferrari, which has tested twice previously with Pirell1 including in April just before the team won the Spanish F1 GP at the same circuit, has not been summoned appear before the tribunal because it used a 2011 car."The key differences in treatment are plain," said Harris, criticising a sporting body run by former Ferrari team boss Jean Todt. "Ferrari was allowed to rely on a verbal confirmation from Pirelli that authorisation had been achieved but apparently Mercedes was condemned for this."Ferrari's dealings with the federation were non-specific about dates, location, names of drivers. It is not criticised but apparently we are. Ferrari was even more involved in the actual testing than us, they booked and paid for the circuit. The team is not criticised."FERRARI NOT SUMMONEDThe lawyer went on to say that Ferrari's test in 2013 was not just a Pirelli test. "One can see from the run sheets... that in the middle of the day they were doing their own thing, but Ferrari is not criticised. It also exceeded 1000km."The rules ban teams from testing with a current car, or one from the previous year, during the season but Pirelli is entitled to carry out a number of tyre tests. The tyremaker argues that it was not a competitor in the championship so was not subject to the same regulations as teams - which the federation disputes."It was a test or track-running by Pirelli," said Harris. "It wasn't undertaken by Mercedes, there's no case."Mercedes says it did not know what tyres were being tested and its drivers used unmarked helmets to avoid unwelcome attention from fans rather than to avoid discovery by rivals.The IAF's lawyer Mark Howard had earlier accused Mercedes of breaking the rules and gaining an unfair benefit, a charge made by Red Bull which protested with Ferrari when the test became known.'DELIBERATELY DEFINED'He told the four tribunal members and president Edwin Glasgow that there was little factual dispute in the case: "There is not much room for doubt that the Mercedes 2013 car was a car covered by the regulations and that the car was subjected to track running-time in Barcelona."Track testing is deliberately defined as track running-time," Howard explained. "It is a term used deliberately because it is unambiguous... any running on the track is deemed to be testing."It is difficult to say that Mercedes gained no benefit from the test."The tribunal heard that Mercedes' sporting director Ron Meadows and principal Ross Brawn, both of whom were at the hearing, spoke to IAF technical head Charlie Whiting on May 2 to ask whether testing with a 2013 car was permissible.Howard added: "What is very odd about all of this is that, on the basis of the phone calls, both Mercedes and Pirelli went ahead without getting back to Whiting and making clear precisely, ultimately, what they were intending to do."He added that any authorisation to test should in any case have been sought from the IAF's World Motor Sport Council and secretary-general Pierre de Coninck rather than Whiting - something Mercedes said Ferrari did not do either.TWO LAWYERS SENTRed Bull's team principal Christian Horner, whose team made a protest against Mercedes at the May 2013 Monaco GP, was attending the hearing along with chief engineer Paul Monaghan.Ferrari sent two lawyers; Mercedes-powered McLaren and Williams also sent legal representatives.e FIA has said a verdict would be issued "as soon as possible" after the hearing.