I haven't much time to say anything substantial on this (I will do in coming days) but I have recently been reading and re-reading this excellent new book on Barth's moral theology. McKenny is Associate Professor of Christian Ethics at the University of Notre Dame. The book is thoroughly engaging and hugely accessible for those wanting to get a grip on the contraversial area of Barth's ethics, and the point he advances - that the analogy of grace is central to Barth's theological ethic - is an intesresting one. What I particularly enjoyed is that McKenny is not an avowed Barthian, but an interested reader who is in some places indebted to Barth and in others not at all. If your library has a copy then I'd say find a quiet afternoon and read it, even if you're not interested in Barth's ethics you will find the engagement between McKenny's keenly trained ethics mind and Barth's ethics-in-the-genre-of-dogmatics hugely rewarding.