(1) Subject to the
provisions of this section, where relief in respect of any payment that has
been made under mistake is sought in any court, whether in an action or other
proceeding or by way of defence, set off, counterclaim or otherwise, and that
relief could be granted if the mistake were wholly one of fact, that relief
shall not be denied by reason only that the mistake is one of law whether or
not it is in any degree also one of fact.
(2) Nothing in this
section enables relief to be given in respect of any payment made at a time
when the law requires or allows, or is commonly understood to require or
allow, the payment to be made or enforced, by reason only that the law is
subsequently changed or shown not to have been as it was commonly understood
to be at the time of payment.