Section 18: Evidence of Customs.

1 Where a custom cannot be established as one judicially noticed, it shall be proved as a fact.

2 Where the existence or the nature of a custom applicable to a given case is in issue, there may be given in evidence the opinions of persons who would be likely to know of its existence in accordance with section 73.

3 In any judicial proceeding where any custom is relied upon, it shall not be enforced as law if it is contrary to public policy, or is not in accordance with natural justice, equity and good conscience.