Mercedes will turn the tables on the FIA at Thursday's hearing in Paris by producing written evidence that they had permission to test Pirelli's tyres.
Mercedes’ trump card is in the form of an FIA email — allegedly from their race director and safety delegate, Charlie Whiting — granting them permission to test.
It is difficult to believe that team principal Ross Brawn would have gone along with the test unless he felt sure of his ground. He said in Montreal last week: “We wouldn't have done the Pirelli test unless we believed we could do the Pirelli test.”
If Mercedes or Pirelli are found guilty they are likely to go the FIA’s international court of appeal in an attempt to get the verdict overturned.
There is even an outside chance that Mercedes could walk away from the sport if they feel they have been dealt with harshly, although that is unlikely given their recent level of investment. If they did exit F1, which they have already considered in recent years, it would leave a massive hole.
Next year McLaren, Force India and Williams are all scheduled to run with Mercedes engines.
Pirelli are also likely to consider their future in F1 if the hearing goes against them. They are already hampered by a lack of in-season testing, and for some time their appeals for help developing the tyres have gone unheeded by the teams.