At the moment the Colour signal light test is the final deciding factor used by the FAA. If you fail all other tests but pass this one then you are given a waiver. I am currently lobbying the AOPA (US) to lobby the FAA for this to become the standard as opposed to a waiver. The reasoning I am using is that the FAA have been issuing this same waiver for a long time (maybee as long as fifty years) and in all that time the NTSB has not one single accident/incident on file where someone with this waiver caused an accident or incident due to mistaking colours. Put simply it is a non issue when it comes to safety. I have been in contact with Dr Pape in Australia and he agrees that if we can get the FAA to do this It will be a "very big stick to beat the JAA with"(my words not his). This may take some time to accomplish but I will post any results here.