Ross Brawn has expressed his disappointment that teams are still arguing about Mercedes\' controversial DRS design. The system uses channels, uncovered when the rear-wing flap is opened, to funnel air to the front of the car and stall the front wing, giving the Silver Arrows a boost in straight line speed. The design was passed legal by scrutineers at the Australian and Malaysian Grand Prix, but on Thursday Lotus launched a formal protest to the FIA. \"It\'s disappointing after three races we\'re still in this situation,\" Mercedes Team Principal Brawn said of the protest. \"The system hasn\'t changed, the FIA\'s position hasn\'t changed, and as far as I understand their argument hasn\'t changed.\" Brawn explained his views on the issue to Sky Sports and repeated his insistence that the Mercedes system conforms to the FIA\'s rules. \"It is part of the DRS system. DRS is there to enhance overtaking and it\'s there to enhance overtaking. It has no other purpose,\" he added. \"There is no limitation on the effect that operating the flap has, and we are operating the flap and gaining as much as we can from the system. \"The flap is driver operated. But that is all that is driver operated.\" Brawn also stated that the system is not a new innovation and was initially passed two years ago. \"In 2010 Charlie stated such a system was legal. It\'s in the minutes of the Technical Working Group meetings,\" said Brawn. \"He stated his opinion then that he considered it legal, so it has not just been going on for three races, but for two years.\"