It would be lovely to get the consensus of the parties, but in an organization that deals with multiple complaints, it can become unwieldy. It's an advantage if you've got a union and you can agree to a roster, so that you've got people available, but people also expect processes to move quickly, and sometimes getting the consent of the parties to use an investigator who's actually available can be very very difficult.
On February 28th, 2018. See this statement in context.