The German Grand Prix stewards have decided to allow Renault to continue using their mass damper system, overruling a clarification by the FIA from last week, which said the system is now banned.
As a result, Renault's hopes of a fightback in this weekend's race have been given a surprise boost.
As autosport.com revealed, the system was outlawed by the FIA shortly after the French Grand Prix amid claims that it was helping improve the aerodynamic performance of cars.
Renault had pioneered the use of mass dampers and were set to suffer the most from the ban.
The team believed, however, that the process by which this system had been outlawed was not correct and duly submitted their spare care at Hockenheim with the mass damper fitted to challenge the ruling.
Although the scrutineers stated that the car was not legal, because it was fitted with the mass damper, the race stewards subsequently got involved and overruled that decision.
A statement issued by the stewards on Friday morning said: "The use of such mass dampers must be considered as permissible."
The stewards cited that there was no specific Technical Regulation that outlawed their use.
There had also been supplied with data, believed to have prepared by Renault, which showed mass dampers did not impact on aerodynamic performance.
The fact that mass damper use was so widespread, and had previously been accepted by the FIA, was also taken into consideration.
Renault have subsequently put the device back on their car ahead of this morning's opening practice session.
Although the stewards have given the green light to the use of mass dampers for now, they have suggested that they will be outlawed in the future.
The statement issued by the stewards said: "On the basis of evidence available to the FIA F1 Technical Department but not available to the Stewards there is seemingly good reason for the FIA's genuine concern as to the future use and escalation in development of mass dampers."
It added: "Whilst finding that on the basis of existing Technical Regulations, the use of mass dampers, is permissible, (it) should not be regarded as an endorsement by the Stewards for any use or further development of such devices beyond the current 2006 Championship, (subject, of course to any change there may be in Technical Regulations on the grounds of safety)."
It's not the first time that the FIA and the race stewards have disagreed.
In 2005, the stewards deemed the BAR-Honda of Jenson Button was legal following the San Marino Grand Prix, only for the FIA to overrule the decision and find their fuel tank was in breach of the regulations.
The team were banned for two races.