tecpilot,
It may be that you are describing a past issue of JAR-OPS. The latest copy has (and has had for a number of years) Subpart O dedicated to the Crew Member other than Flight Crew.
The requirement for specific HEMS training and checking is contained in Appendix 1 to JAR-OPS 3.005(d) paragraph (e)(2) - you might look at it again because it is quite comprehensive.
Because there may be circumstances where the HEMS crew member may be required down the back, there cannot be an absolute requirement for him/her to be seated in the co-pilots seat; however, it is specified in ACJ to Appendix 1 to JAR-OPS 3.005(d) sub-paragraph (c)(3)(iv), as are the specific duties.
The requirement for two pilots at night is contained in the HEMS appendix - which contains a derogation for a pilot and a HCR under specific circumstances and for which Approval from the operational authority is required (similar to the type of conditions contained in the OpsSpec mentioned below - i.e. for local operations).
No, it is not perfect but does provide a skeleton on which a good HEMS operation can be hung.
As a matter of interest I see that the FAA is just about to publish, for comment, new OpSpecs "A021 Helicopter Emergency Medical Services (HEMS) Operations" and "A050 Helicopter Night Visions Goggle Operations (HNVGO)" which contain detailed site, qualification, dispatch and weather criteria.
What hasn't been established yet is the actual accident rate (only the headline figures); it is also clear that there are few recognisable patterns in the accidents; even the human factors issues are complex. It will take a great deal of analysis before any specific measures can be decided. What does appear to be evident (from the reports as well as from commentaries in this and other threads) is that there needs to be a culture change.
Jim