The report that was recently produced by a congressional committee talks about how certification was done between the FAA and Boeing. I'm going to let the report speak for itself.
However, I can tell you that in Canada, when we certify our aircraft, we choose the delegates who work for the company and who will help us with the certification very carefully. For example, when we certified the Bombardier C Series, even though Transport Canada employees had spent 160,000 hours doing the certification, there were also delegates who helped us in that process. And in fact, it wasn't Bombardier that chose them, it was us.