Mark Thompson wrote on Tue, Sep 24, 2002 10:10 PM EDT:
Question on castling (and championing and centauring): You can only castle
if your 'king has not been checked at any previous time in that game' --
by 'previous' do you mean to exclude the current time? That is, are you
allowed to castle while in check in this game?
There is nothing in the rules prohibiting moving the king across an
attacked square while castling, so I assume that's legal here.