It is trite law that one of the main purposes of tax treaties is to prevent double taxation of the same income. In Canada this principle has often been treated with a grain of salt since Canadian domestic rules do not bar double taxation and, in fact, the Canada Revenue Agency often resorts to double taxation where, for example, a shareholder appropriation is disallowed as a corporate expense while fully taxed in the shareholder’s hands.
The recent decision of the Federal Court of Appeal in The Queen v. Sommerer illustrates a refreshing approach to the concept of double taxation, at least in the context of Canada’s network of bilateral tax treaties based on the OECD Model Convention (and, to a lesser extent, the UN Model Convention).
Mr. Sommerer was at all material times a resident of Canada. He was a contingent beneficiary of an Austrian Privatstiftung (the “Sommerer Private Foundation”) created by his father in 1996. The Sommerer Private Foundation was at all material times a resident of Austria for the purposes of the Canada-Austria Tax Treaty. The facts that gave rise to the assessments under appeal are summarized by Sharlow JA as follows:
 On October 4, 1996, Peter Sommerer sold to the Sommerer Private Foundation 1,770,000 shares of Vienna Systems Corporation (the “Vienna shares”) for their fair market value of $1,177,050 (66.5¢ per share). The Sommerer Private Foundation paid $117,705 of the purchase price on the date of the agreement and was legally obliged to pay the remainder at a later date, with interest. The sale was unconditional. The cash portion of the purchase price was paid using part of the initial endowment from Herbert Sommerer (paragraphs 67 and 88 of Justice Miller’s reasons).
 In December of 1997, the Sommerer Private Foundation sold 216,666 of the Vienna shares for $4.50 per share to three individuals unrelated to the Sommerer family, realizing a capital gain. In December of 1998, the Sommerer Private Foundation sold the remaining Vienna shares to Nokia Corporation for $9.00 per share, realizing a further capital gain.
 In April of 1998, Peter Sommerer sold to the Sommerer Private Foundation, unconditionally, 57,143 shares of Cambrian Systems Corporation (the “Cambrian shares”) for $100,000 (approximately $1.75 per share). In December of 1998, the Sommerer Private Foundation sold the Cambrian shares to Northern Telecom Limited for $14.97 (US) per share, plus a further $4.12 (US) per share conditional on certain milestones being met in 1999. That sale resulted in another capital gain for the Sommerer Private Foundation.
CRA assessed Mr. Sommerer on the basis of subsection 75(2) of the Income Tax Act alleging that the proceeds from the sale of the shares by the Foundation could possibly revert to Mr. Sommerer. Both Justice Campbell Miller in the Tax Court of Canada and Justice Sharlow in the Court of Appeal rejected that interpretation holding that subsection 75(2) could not apply on a sale of property at fair market value.
Justice Sharlow did not stop there however. She went on to agree with Miller J. that the position advocated by CRA violated the Treaty’s fundamental principle of avoiding double taxation:
 The OECD model conventions, including the Canada-Austria Income Tax Convention, generally have two purposes – the avoidance of double taxation and the prevention of fiscal evasion. Article XIII (5) of the Canada-Austria Income Tax Convention speaks only to the avoidance of double taxation. “Double taxation” may mean either juridical double taxation (for example, imposing on a person Canadian and foreign tax on the same income) or economic double taxation (for example, imposing Canadian tax on a Canadian taxpayer for the attributed income of a foreign taxpayer, where the economic burden of foreign tax on that income is also borne indirectly by the Canadian taxpayer). By definition, an attribution rule may be expected to result only in economic double taxation.
 The Crown’s argument requires the interpretation of a specific income tax convention to be approached on the basis of a premise that excludes, from the outset, the notion that the convention is not intended to avoid economic double taxation. That approach was rejected by Justice Miller, correctly in my view. There is considerable merit in the opinion of Klaus Vogel, who says that the meaning of “double taxation” in a particular income tax convention is a matter that must be determined on the basis of an interpretation of that convention (Klaus Vogel on Double Taxation Conventions: A Commentary to the OECD –, UN –, and US Model Conventions for the Avoidance of Double Taxation on Income and Capital, 3rd ed. (The Hague: Kluweer Law International, 1997)).
 I see no error of law or principle in the conclusion of Justice Miller that Article XIII (5) applies to preclude Canada from taxing Peter Sommerer on the capital gains realized by the Sommerer Private Foundation.
Unless this case is reversed by the Supreme Court of Canada (at the date of this comment, no leave application has been filed), it is likely to be a very important precedent for tax practitioners plying their craft in the highly complex area of international tax treaties.