Collins & Aikman Products Co. v. The Queen, 2009 DTC 1179 [at at 958], 2009 TCC 299, aff'd 2010 DTC 5164 [at 7293], 2010 FCA 251 -- summary under Retroactivity/Retrospectivity

In an obiter indication that ss.152(1.11) and (1.12), pursuant to which the Minister had made a retroactive redetermination of paid-up capital, should likely be interpreted restrictively, Boyle, J. stated (at para. 28) that "instinctively, it seems that retroactive determinations, like retroactive tax legislation, should be avoided except in cases where the legislator has clearly and unambiguously set out its intent to impose or permit the tax to be imposed retroactively."