In an earlier post I had a look at the role played by design authorities in an organisation, which can have a major affect upon both safety and project success. My focus in that post was on the authority aspect.
However another perspective on the role that a design authority performs is that of someone who is able to understand both the operational requirements for a system (e.g. those that define a need) as well as the technical (those that define a solution) and most importantly be able to translate between them.
This is a role that is well understood in architecture, but one that has seemed to diminish and dwindle in engineering where projects of any complexity are more often undertaken by large bureaucratic organisations, which also traditionally fear assigning responsibility to one person.