In the Supreme Court of Canada.

(On appeal from the Federal Court of Appeal)

BETWEEN:

POTASH CORPORATION OF SASKATCHEWAN INC.

APPLICANT (Appellant)

--and--

HER MAJESTY THE QUEEN

RESPONDENT (Respondent)

Affidavit of Mario M. Tombari

On February 6, 2004, Tax Executives Institute filed the following affidavit with the Supreme Court of Canada in support of Potash Corporation of Saskatchewan's appeal of a decision denying PCS's amendment of a notice of appeal. TEI's affidavit, which marks the first time TEI has become involved in a court case in Canada, urges the Supreme Court to review the case because the issues have national significance affecting all large coporations. The affidavit, which was prepared under the aegis of TEI's Canadian Income Tax Committee, was signed by TEI's Vice President for Canadian Affairs, Mario M. Tombari, of Imperial Tobacco Limited.

I, MARIO M. TOMBARI, of the City of Montreal, in the Province of Quebec, MAKE OATH AND SAY:

1. I am currently the Vice President for Canadian Affairs for Tax Executives Institute ("TEI" or the "Institute") and serve on the nine-member Executive Committee of the Institute's Board of Directors. TEI is a voluntary, non-profit association of corporate and other business executives, managers, and administrators who are responsible for the tax affairs of their employers. The Institute's Executive Committee is vested with the authority to manage the day-to-day operations of TEI, including the deliberation and approval of all Institute positions on public policy matters. In addition to serving as the 2003-2004 Vice President for Canadian Affairs of TEI, I am the Corporate Income Tax Director for Imperial Tobacco Canada Limited of Montreal, Quebec. I am, however, making this affidavit in my capacity as TEI's Vice President for Canadian Affairs rather than as a representative of my employer.

2. TEI was organized in 1944 and has approximately 5,400 members who represent more than 2,800 of the leading businesses in Canada, the United States, and Europe. The Institute is dedicated to promoting the uniform and equitable enforcement of the tax laws and to reducing the costs and burdens of administration and compliance to the benefit of both the government and taxpayers.

3. TEI members represent a cross-section of the business community with representatives from most major industries, including manufacturing, distributing, wholesaling, and retailing; real estate; transportation; financial services; telecommunications; and natural...