Hamilton and Leclerc, who finished second and sixth respectively in the 56-lap race won by Max Verstappen, were being investigated by the stewards following a plank wear inspection in Austin.
The original report from FIA technical delegate Joe Bauer stated: “A physical floor and a plank wear inspection was carried out on car numbers 16 [Leclerc] and 44 [Hamilton].
“The skids located in this area are found to be not in compliance with Article 3.5.9 e) of the 2023 Formula One Technical Regulations. I am referring this matter to the stewards for their consideration.”
Personnel from both Mercedes and Ferrari were summoned to see the stewards and, just after 7pm local time in Austin and more than three hours after the race finished, their disqualification from the race was confirmed.
Hamilton therefore loses the 18 points earned from his second-place finish, while Leclerc loses eight points.
Both drivers, however, do have the right to an appeal but it is understood Mercedes will not appeal the FIA’s verdict.
In a Mercedes press release, Hamilton stated he was simply “disappointed” with the penalty, while team boss Toto Wolff admitted “we got it wrong.”
The FIA note reveals that the cars of Verstappen and Lando Norris (who now moves up to second from third in the final classification) were also inspected, but passed the checks.
The section of the rulebook referred to reads: “The thickness of the plank assembly measured normal to the lower surface must be 10mm [plus or minus] 0.2mm and must be uniform when new.
“A minimum thickness of 9mm will be accepted due to wear, and conformity to this provision will be checked at the peripheries of the designated holes.”
The ruling means Williams driver Logan Sargeant earns his first F1 point in bizarre circumstances at his home race.
The final stewards report said: “During the hearing, the team acknowledged that the measurement performed by the FIA Technical Team was correct and stated that the high wear on the skid pads was probably a result of the unique combination of the bumpy track and the Sprint race schedule that minimized the time to set up and check the car before the race.
NEW TOP-10 - UNITED STATES GRAND PRIX
1. Max Verstappen
2. Lando Norris
3. Carlos Sainz
4. Sergio Perez
5. George Russell
6. Pierre Gasly
7. Lance Stroll
8. Yuki Tsunoda
9. Alex Albon
10. Logan Sargeant
“The Stewards note that the onus is on the competitor to ensure that the car is in compliance with the regulations at all times during an event.
“In this particular case, the rear skid in the area defined in the Technical Delegate’s report was outside of the thresholds outlined in Article 3.5.9 e) of the FIA Formula One Technical Regulations, which includes a tolerance for wear.
“Therefore, the standard penalty for a breach of the Technical Regulations is imposed.”
Breaches of technical checks of the car often result in disqualification, with a recent example being Hamilton from qualifying in Brazil in 2021.
Michael Schumacher was disqualified from the 1994 Belgian Grand Prix for an illegal floor, allowing Damon Hill to win the race.
Hamilton was already in hot water with the FIA for an unrelated matter, after crossing a live track at the last race in Qatar and was spoken to again in Texas due to his status as a “role model.”
Leclerc started Sunday’s race on pole but, opting for a different strategy, fell behind after Norris stole a march on the Ferrari at the start.
Hamilton, meanwhile, came close to victory after reeling in Verstappen - who was booed on the podium - at the end.
The 38-year-old has not won in nearly two years, with his last victory coming in Saudi Arabia in December 2021, but this disqualification will be a bitter pill for the seven-time world champion to swallow ahead of the next race, this weekend in Mexico.