Many modern constitutions, at least Continental European Constitutions, are based on "Convention for the Protection of Human Rights and Fundamental Freedoms", drafted in 1950, and signed by European States, according to which, "Right of privacy" and "right of communication" is an essential human right and "Essential rights can only be restricted by law, for a well determined duration".
So, this kind of, "access", requires absolutely a law, in any modern law system.
And, in many countries, it already exist such laws, for traditional ways of communication: GSM operators must provide ways to legal authorities to "listen an individual, clearly stated communication", for a "specified time", by a "judge decision or court order".
Easy way is to find a "central source" of communication and to hold that entity responsible to "provide required ways".
The solution for legal, "targeted" access to private data(which I have been defending for many years) is NOT encryption backdoor.
It's simply, "hardware or operating system level backdoors". And we also know that those backdoors exist for a very very long time: Check Wikileaks documents in order to learn about a few. Ask Google for very old Intel Chip "undocumented opcodes" etc.
So, there isn't any problem for "targeted" access to any kind of private data.
There are device and/or OS specific backdoors & malwares used also by governments for many years(also see Wikileaks and many other sources for more info).
They just need to "legalize" a "de facto" truth: Asking hardware and/or operating system level backdoors passwords by a legitimate court order in case of strong suspicion(In fact, they are actually and legally doing this for regular phone calls, with court orders. They must just pass a new law for operating system/hardware level access to devices).
Regarding all those "facts", still insisting on "encryption backdoor" is a cheap demagogy in order to cover their appetite for "mass surveillance" passions.
And Mrs. Cannoy, I don't think you have right to "silently discard" my messages without any reason. Please don't do that anymore.