Proof, compliance and data
Reliable copy
Under French law, a reliable copy has the same evidential value as the original; reliability is assessed by the judge, unless a decree presumes it.
The Civil Code sets the principle, and a 2016 decree specifies when a copy is presumed reliable: an irreversible paper reproduction, or an electronic copy whose integrity is guaranteed by means such as a timestamp or a digital fingerprint, with a record of the operations. A copy that does not meet these conditions is not worthless, but its reliability must be proven.
Why it matters for fax
Fax by nature produces a copy: the recipient never receives the original. The notion of a reliable copy explains why keeping the file sent, linked to its proof of transmission, matters as much as the sending itself.