French police intercepted a 48-year-old Swiss manager driving a Porsche 911 GT3 at 312 km/h on the A40 motorway in the Arve Valley, Haute-Savoie, on September 27, 2026. After applying the official technical margin of tolerance authorities recorded the speed at 300 km/h on a 130 km/h stretch, marking what media reports indicate as the highest speed ever detected by law enforcement during a control.
The driver, returning from a rally, faced immediate administrative penalties including license withdrawal, vehicle seizure, and a 1,500 euro deposit before a scheduled court appearance. French regulations state that exceeding the limit by at least 50 km/h is a criminal offense on the first infraction, carrying a maximum sentence of three months in prison, a fine up to 3,750 euro, license suspension or cancellation, and vehicle confiscation.
Defense Argues Radar Measurement Exceeds Device Certification Limits
Despite the severe penalties, the motorist’s legal defense centers on a technical loophole regarding the speed-measuring device. Traffic law specialists Maître Changeur and Rémy Josseaume noted that mobile radar units are typically certified up to 250 km/h, while newer models may reach 300 km/h according to legal experts. Because the recorded speed exceeded these operational thresholds, lawyers argue that the measurement may be technically invalid for speeds surpassing the device’s homologation limit.
Pending Judicial Review
The case is set to reach the tribunal in Bonneville next February where the court will evaluate whether the radar’s certification limits invalidate the prosecution’s primary evidence. Authorities have not yet clarified how the French proceedings will impact the driver’s Swiss driving license outside of France.
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