  We show the equality of the local Asai L-functions defined via the
Rankin-Selberg method and the Langlands-Shahidi method for a square integrable
representation of GL(n,E). As a consequence we characterise reducibility of
certain induced representations of U(n,n), and the image of the base change map
from U(n) to GL(n,E) in terms of GL(n,F)-distinguishedness.
