The arm’s length comparable in transfer pricing: a search for an “actual” or a “hypothetical” transaction?

When searching for an arm’s length comparable in the transfer pricing analysis, does the analysis require (or allow) searching for a transaction that actually took place in the market, or can/should the internal data of the controlled transaction simply be imputed to form a hypothetical uncontrolled transaction in which the parties are assumed to be operating at arm’s length but otherwise dealing under the same circumstances? This article sheds light on this question, based on lessons distilled from recent Canadian jurisprudence; particularly, the case Canada v. GlaxoSmithKline Inc. The author calls on Canada’s courts to reconsider their approach to this issue, and alerts courts in other jurisdictions to avoid transplanting the Canadian approach because otherwise they would risk repeating the same mistake(s).