HN39,
Isn't that exactly what the systems do when A/P, A/THR and "Normal Law" protections step back and say "your airplane"?
Not exactly.
From FCOM / ALT LAW 1 / Pitch control[INDENT]"Flight law is a load factor demand law, similar to normal law, with limited pitch rate, feedback and gains,
depending on speed and configuration."
... / ALT LAW 2 / Pitch control
Identical to ALT 1 law"
Note the ambiguity: nothing is said
in case Alt law 2 is due to ADR faults or disagree conditions.
We can think that in this case (ADR DISAGREE) pitch control uses a default airspeed value or default gains that mitigate the missing data. I suspect that there are potential problems in the "return to normal" sequence, i.e. when airspeed sources become asynchonously available again. Remember invalid airspeed events sometimes were very short.