http://www.eurodressage.com/equestrian/2011/06/07/fn-training-semin...

Ok.  Here it is!.   Read the whole article and you will find that it was demonstrated ALL of the GP dressage movements in a bitless bridle.   The image shown clearly demonstrates the 'incorrect' frame which contridicts the rules of dressage.

The fact remains.....GP dressage can be done bitless and therefore there is no reason not to make it legal in competitions.