In the FIA's statement on the matter on Wednesday, it said the protest from Racing Point was regarding "an alleged breach of the sporting and technical regulations and the FIA International Sporting Code, relating to a 'pre-set lap distance-dependent brake bias adjustment system"'.
FIA stewards came to the conclusion that Renault's brake bias system on the cars was not pre-set, but it did constitute a driver aid and sporting regulations were breached.
In their decision, it noted that the disqualification is a more severe punishment for being found in breach of Article 27.1, which states a driver must control the vehicle alone and aided, but the potential advantage from the system Renault was running is greater than more recent cases.
Renault has been given the right to appeal this decision, but as it stands, their disqualification brings Racing Point's Lance Stroll and Toro Rosso's Daniil Kvyat to ninth and tenth places, respectively.
The FIA concluded that the system, therefore "does not breach" the technical regulations.
The Renault F1 team is considering its next move following the disqualification of Daniel Ricciardo and Nico Hülkenberg from the Japanese Grand Prix because their cars were deemed to be illegal.
Renault was given until 10am on Thursday in Mexico City to appeal the decision, but declined to do so.
"Renault F1 Team acknowledges the decision of the Stewards of the Japanese Grand Prix regarding the protest by SportPesa Racing Point F1 Team concerning the legality of Renault F1 Team's braking system during the Japanese Grand Prix", they said in a statement.
After impounding the steering wheels and Electronic Control Units from Renault's cars in Japan, the stewards at the race submitted the arguments of both teams to the FIA's technical department.
The team also felt Renault had breached Articles 11.1.3, 11.1.4 and 8.6.3 of the technical regulations that outlaw powered devices that alter brake balance, or any system not controlled by the driver.
"Nevertheless, it is still an aid and, therefore, contravenes [the regulations]", the race stewards stated. "It is what we have always done and will continue to do, albeit with stronger internal processes before innovative solutions are brought on track".
"The brake balance adjustment system in question acts as a driver aid, by saving the driver from having to make a number of adjustments during a lap".