Episode 7 said that Acts which change legal rights or liabilities are presumed not to apply retrospectively. This case says further (at [47-51]) that the presumption chiefly applies to Acts that change the law, not the exercise of existing statutory powers10.
The Commissioner had exercised a statutory discretion to group and re-assess ‘related corporations’ for the past 5 years. Croft J said this was not retrospective – it just applied then existing law to past circumstances. The taxpayers’ liabilities weren’t retrospectively altered as they were always subject to the potential exercise of the discretion during the assessment process.
This case is from Episode 14 of interpretationNOW!