The OMX-case entailed considerable uncertainty about the relationship between tax treaties and Swedish domestic law. Previous approaches to handle rule conflict between them was put out of action for the first time when an internal rule took precedence over tax treaties. The Greece-case came a few years later where there were hopes that it would be decided in plenary session to return to the view that prevailed before the OMX-case, which did not happen. Instead the Supreme Administrative Court ruled that the tax treaties shall in principle be given preference, but that in exceptional situations tax treaties can be infringed to an internal rule's benefit, so called tax treaty override. Such procedure is acceptable if the legislature gives "clear expression" of the intention of a certain type of income is to be taxed in Sweden, or that a particular new rule applies regardless of the provisions in tax treaties.

The purpose of this thesis is to analyze the supreme administrative courts management of rule collision between domestic law and tax treaties in the Greece-case. Further analysis of the requirement "clear expression" shall take place and the basis of why the supreme administrative court justifies tax treaty override shall also be analyzed.

The conclusion presented in this thesis initially includes problems that arise to conclude the meaning of the term "clear expression" and that application difficulties arise because the supreme administrative court did not provide further guidance of its meaning. Secondly, that the supreme administrative court justify tax treaty override occasionally since there is no constitutional or procedural obstacles for a newer internal law to expand the Swedish taxation when an already implemented taxation agreement restricts it.