Article 3.6.2 of the ACO's technical regulations allows two aerodynamic elements at the front of the car, but beyond that, "Any bodywork element the function of which is only to generate down force" is prohibited. Said Aston Martin's race head after the car was questioned at March's 12 Hours of Sebring, the components act "exactly like a flap on a wing, with the splitter arrangement acting as the main plane."
Peugeot raised its concerns earlier this year, but the Audi has been scrutinized every race since. Peugeot says it doesn't want to hurt the competition, it simply wants the rules clarified. However, if the Le Mans stewards rule against the French team, it says it will take its case all the way to the FIA. And if that happens, Sunday's result will be unofficial until the high racing court decides. Thanks for the tip, mforty!