I posted this under a different topic but here it is again.
according to the JAA the door may be open to the signal light test.
here are the relevant links.
http://www.jaa.nl/jar/jar/jar/jar.fcl.3.1.a.3.125.htm
and
http://www.jaa.nl/jar/jar/jar/jar.fcl.3.1.a.3.045.htm
The regs were written in general terms so they do not apply specifically to colour vision however here are the important points.
Under JAR 3.045 "Special Circumstances"
"An exemption may be granted where the application of JAR-FCL would have anamalous consequences."
Clearly the fact that a FAA licensed pilot with a SODA for colour vision can legally fly a N registered aircraft commercially in JAA airspace but would be denied the possibility of flying a JAA reg aircraft in the same airspace is an "Anamalous Consequence"
"An Exemption may be granted if it can be shown that an equivalent level of safety would exist."
The evidence of an equivalent level of safety is overwhelming. The FAA have been issuing SODA's for many many years and to date no one with a SODA has crashed or had an incident where the cause was determined to be poor colour vision. The FAA thorougly researched this before they began issuing SODA's and have a large body of evidence to support and validate the signal light test.
Dr Pape in Australia has taken it a step further and proved this to the satisfaction of the courts.
FCL 3.125 allows for the ability and skill of the applicant to be considered. It also suggests a medical flight test if appropriate.
I live in the USA an I am in the process of getting my instrument rating and I intend to get my commercial and multiengine ratings also. I have a current First Class medical with a SODA for Color vision.
Good luck to anyone who takes on the JAA I'm sure that you will meet a lot of resistance but keep at it.