In any marginal question of statutory interpretation, evidence that it has been interpreted in a consistent way for a substantial period of time by those responsible for the administration of the legislation is admissible.

The evidence may be relevant to tip the balance in favour of a particular interpretation. It is consistent with the modern approach to statutory interpretation that examines the words in context and seeks to determine the meaning that should reasonably be placed on the words. The conduct of those who administer the legislation provides clear evidence of how reasonable persons in their position would understand and construe the provision.

In the case of The Commissioner for the SARS v Bosch the revenue authorities had adopted a certain interpretation for eight years which was held to fortify the taxpayers’ contentions as to the meaning of the section.

It was also found that the fact that parliament was about to amend the section was a guide to parliament’s understanding of the existing section.