Hope this is useful:
In this chapter, I discuss the role of the native speaker in applied linguistics and set out the different interpretations of the concept. I begin with the issue of the native speaker as identity; then I consider various definitions of the concept. I then examine the relation between the native speaker and the non-native speaker and raise the question of whether a second or foreign language learner who starts learning after puberty can become a native speaker of the target language. This brings us back to the issue of identity: I consider four ways of coping with the issue of loss of identity as a native speaker. I conclude that the native speaker concept remains ambiguous, necessarily so, since it is both myth and reality.
http://www.arts.ed.ac.uk/celtic/poileasaidh/daviesseminar.html