I found his analysis of the origins of the terms used in biblical translation and Christian theology immensely helpful, especially the transition from ancient Hebrew to koine Greek to Vulgate Latin. I couldn't quite get all the transliteration he uses to work in HTML, but I've copied out a couple of paragraphs below in the hope they might be thought-provoking and useful.
Note especially his insistence that 'righteousness' must be understood within the framework of personal covenantal relationship. The bit that has consistently stuck with me, I have put in bold.
Anonymous users wishing to paste in the comments box need first to select 'preview', then close the preview box. When posting your comments please give a full name and location. Comments without this information may be deleted.The oldest meaning of sedāqâ, as judged by its use in the Song of Deborah (Judges 5.1-31), appears to be ‘victory’. [...] In this early passage ... God is understood to have demonstrated his ‘righteousness’ by defending Israel when her existence was threatened by an outside agency. Underlying this understanding of iustitia Dei is the conceptual framework of the covenant: when God and Israel mutually fulfil their covenant obligations to one another, a state of righteousness can be said to exist – i.e., things are saddîq, ‘as they should be’. Thus Israel’s triumphant victories over her enemies were seen as proofs of the sidqôt ’adonay, the iustitiae Dei of the Vulgate. [...]It is to the genius of [H] Cremer [Die paulinische Rechtfertigungslehre im Zusammenhang ihrer geschichtlichen Voraussetzungen (Guttersloh, 1899)] that we owe the fundamental insight that sedāqâ, in its basic sense, refers to an actual relationship between two persons, and implies behaviour which corresponds to, or is consistent with, whatever claims may arise from or concerning either party to the relationship. The relationship in question is that presupposed by the covenant between God and Israel, which must be considered as the ultimate norm to which sedāqâ must be referred. The Hebrew concept of sedāqâ stands in a class of its own – a class which Cremer brilliantly characterised as iustitia salutifera [‘salvation righteousness’, as distinct from iustitia distributiva, ‘distributive righteousness/justice’, according to ‘dues’ or ‘merits’].Alister E McGrath, Iustitia Dei: A history of the Christian doctrine of Justification, Vol 1, (Cambridge: University Press, 1986) 7-8