Jack Bernstein, Barbara Worndl, & Kay Leung (all of Aird & Berlis, Toronto) have published Canadian Supreme Court’s Pronouncement on GAAR:  A Return to Uncertainty, also available on the Tax Analysts web site as Doc 2005-21313, 2005 WTD 204-10.  Here is the abstract:

The Supreme Court of Canada on October 19 issued its long-awaited decisions in Mathew v. Canada and Canada Trustco Mortgage Co. v. Canada. The two decisions are the Supreme Court’s first pronouncement on the application and interpretation of Canada’s general antiavoidance rule. The GAAR was first introduced in Canada in the Income Tax Act (ITA) in 1988. The purpose of the provision was to distinguish between legitimate tax planning and abusive tax avoidance. In essence, the GAAR is meant to prevent abusive tax avoidance transactions while recognizing taxpayers’ need for certainty in planning their affairs. The GAAR did not receive any judicial consideration until the late 1990s, and it was not until the new millennium that the Federal Court of Appeal issued its first decision on the interpretation of the GAAR in OSFC Holdings Ltd. v. The Queen, 2001 DTC 5471 (FCA).