I believe the first article I read about the "end of the billable hour" as a mechanism for recording attorney work output and ultimately client bills was in the mid-1990s. I am sure there were more before then, but I just do not recall. The arguments then (as now) revolved around transparency, documentation, and proving the value chain. Client resistance to paying a "for services rendered" invoice was believed to be so significant that no client would pay them and no law firm dared to render them.