Hello Sandeep and Phil,
As Phil has said, 'would' gives the sentence a hypothetical sense (Second Conditional). 'will' is a prediction of something probably happening in the future:
Conditional 2 (improbable/hypothetical): We are not going to introduce such a policy because (if we did,) it would not be constitutional.
Conditional 1(probable): It is risky to introduce such a policy because (if we do,), it will not be constitutional.
In the other example, the same logic can apply if we are actually discussing what's currently going on in a tribal setting. However, there's another possibility, and that is describing how things used to work in the past (using 'would' as an alternative to 'used to'):
In that culture, whenever a chief died, his son would inherit all his dominions.