David Duff


Relevant Thesis-Based Degree Programs


Graduate Student Supervision

Doctoral Student Supervision

Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.

Border carbon adjustments in support of domestic climate policies: explaining the gap between theory and practice (2019)

A growing number of scholars, environmentalists, politicians, and business leaders have recommended border carbon adjustments (BCAs) to support domestic climate policies. BCAs can levy a domestic carbon price on imports. By extending domestic policies beyond a jurisdiction’s boundaries, BCAs can put domestic and foreign industries on a level playing field, counter carbon leakage, and incentivize other jurisdictions to take climate action. In theory, BCAs offer the promise of environmental, economic, and political benefits. However, despite their potentially substantial benefits and backing from prominent leaders, BCAs are largely absent in practice. Although an increasing number of carbon-pricing policies have been adopted throughout the world, very few examples of BCAs exist, and so far none have been implemented at a general scale in any jurisdiction. In order to explain this puzzle and investigate the conditions under which policy-makers do, or do not, adopt and implement BCAs, this research empirically tests a series of hypotheses using four case studies of experiences with BCAs in the European Union (EU) and in California. The case studies comprise the inclusion of international flights in the EU’s cap-and-trade system, stationary installations in this system, the inclusion of electricity imports in California’s cap-and-trade program, and industrial facilities in this program. This research draws on information from 43 expert interviews and a wide range of published materials, including quantitative data. The research finds several barriers that prevent the adoption and implementation of BCAs in practice. Policy-makers are likely to meet domestic political opposition to BCAs, may run into opposition from other governments, and may encounter concerns about the circumvention of BCAs. In fact, domestic industry stakeholders overwhelmingly oppose BCAs since they prefer alternative measures, such as free allocation of emission allowances. They also oppose because BCAs may result in a stakeholder’s increased exposure to carbon pricing, and export-oriented industries fear trade war and retaliation from other jurisdictions. Therefore, the circumstances in which BCAs may be implemented successfully, and thus the scope for applying BCAs in practice, appear to be more narrow than acknowledged in the literature.

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Master's Student Supervision

Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.

Sustaining the corporate income tax rates of small businesses in developing economies : lessons for Nigeria from Canada, South Africa, and the UK (2022)

The Nigerian government recently introduced zero and low corporate income tax (“low CIT”) rates for small and medium companies to, amongst other reasons, foster the growth of small businesses in the country. Nigeria is not the first country to introduce such CIT incentives for small businesses. Similar incentives exist in Canada and South Africa and previously in the United Kingdom (“UK”).Policymakers are quick to argue that low CIT rates encourage the growth of small businesses, however, evidence shows that the implications of such CIT rates often defeat their purpose and may have unintended consequences on the tax system, especially resulting in tax arbitrage behaviours and inappropriate tax avoidance arrangements. Notably, this happened in the UK, when a low CIT rate was introduced in 1999 for small companies. The low CIT rate triggered tax-motivated incorporations to, amongst others, shelter personal income and avoid higher personal income tax rates. The UK government considered this as unacceptable and eventually eliminated the low CIT rates in 2006. In other countries, like Canada and South Africa, where these low CIT rates exist, tax anti-avoidance rules are therefore introduced and improved to curb inappropriate tax avoidance arrangements. Many of these rules do not currently exist in Nigeria.Studies have also shown that, in addition to making the tax system complex and complicated, these tax anti-avoidance rules do not end up curbing all forms of tax avoidance schemes and countries still suffer significant loss of vital tax revenue. Experts therefore suggests having neutral tax system with no targeted low CIT rates.In adopting both the doctrinal methodology and comparative law approach of legal research, this study analyzed the experiences in the UK, Canada, and South Africa, and shows that it is not a good idea to provide low CIT rates for small businesses in Nigeria, given its serious implications. In recommending the options of either withdrawing the low CIT rates or retaining same but introducing new tax anti-avoidance rules, this study shows that irrespective of whatever option the Nigerian government chooses, the current Nigerian CIT system is not ideal and needs to be amended.

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