How in the world anyone can disagree with lex orandi, I don’t know…
Barth, of course, in his late writings on ethics, gave a related but distinct account of the relation of liturgy and ethos (an account with which Jüngel is closely familiar). For Barth, invocation of God is the first action of the Christian ethos:97 the law of prayer (lex orandi) is the law of action (lex agendi). This is not only because it makes human action a passive (darstellend) celebration of prior divine acts, but also (and, for the late Barth, more importantly) because it requires that human moral action correspond in its sphere to the work of God in Jesus Christ, to which it testifies in analogous human action. The tension between this model and what we have already seen of Jüngel’s use of justification in the context of discussing ethics is worth exploring at greater length.98
97 ChrL, pp. 36–46.
98 Jüngel has been one of the major commentators on Barth’s ethics of reconciliation, as well as one of its chief defenders against misunderstanding: see his various pieces ‘Karl Barths Lehre von der Taufe’, ‘Thesen zu Karl Barths Lehre von der Taufe’ and Zur Kritik des sakramentalen Verständnisses der Taufe’, in Barth-Studien, pp. 246–90, 291–4, 295–314. Jüngel (with H.-A. Drewes) edited ChrL for the Swiss Gesamtausgabe, and published a commentary on the material, ‘Invocation of God’.
 John Webster, Barth’s Moral Theology: Human Action in Barth’s Thought (London; New York: T&T Clark, 2004), 198.