jcjeant,
I think you are getting the cart placed in front of the horse. It is not a "law problem," so far. Determination of the causes or probable causes have not been determined as of yet. The BEA has the responsibility to investigate the accident, assemble all of the available data and evidence, consult with any entity that may provide greater insight into the potential meanings of the evidence and data including providing of specific information to enable testing and confirmation of potential findings, followed by assembling a final report based on the pertinent data and supporting findings as to causes, probable causes and undetermined causes. At the conclusion of the BEA's investigation the final report is issued and presented to the responsible French Court. At the time this transfer occurs, it then become a "law problem" to be resolved. Prior to this report, no party of interest that cannot contribute to in depth understanding, i.e., technical expertise or human behavior as it pertains explicitly to the accident should have access to the full actual data.
The BEA can (as does the NTSB in the US) choose to release certain preliminary information to the general public it has found to be pertinent and indicate what other tasks are being performed in its investigation as it proceeds towards conclusion. The BEA has chosen to do this through interim reports. The BEA may also decide to privately apprise the families of the victims, out of courtesy, of their investigation methodology, status, etc., perhaps more in detail than what may be released to the general public. It is the BEA's call, but nothing is owed in advance of the final report being written and turned over the French Court.
I am not aware of any highly technical aircraft accident investigation where the investigative body could not consult with the airline operator, aircraft, engine or avionics manufacturers to gain additional knowledge of the system or systems, while sharing available need to know data to hopefully enable correct conclusions to be drawn. It doesn't mean the lawyers to be involved in the future litigation are entitled to this exchange of information at the actual time the exchange occurs.
Dozy is correct in his assessment!
Welcome back
Dozy
TD