Pre-season
At Australian Grand Prix and the Malaysian Grand Prix an official complaint was launched by other teams against the rear diffusers of the Williams FW31, Toyota TF109 and the Brawn BGP 001 saying that they were illegal, but after analysing the cars the FIA reported that the cars weren't illegal. The teams appealed and after much deliberating the car were deemed legal by the FIA.
Read more about this topic: Toyota TF109