A comparative approach was used in this study, on the grounds that countries can benefit from learning from one another. A systematic examination of drug regulation and its environment across countries can help shed new light on a country situation, provide a new perspective on the constraints facing it, and suggest options for improvement. There are three basic reasons for conducting systematic comparisons between countries (16).

1. Strategy development: comparing different ways of managing similar problems can suggest both positive and negative lessons, i.e. guidance on what to do and what not to do. Comparing cross-country experiences is a useful way of developing policy instruments for problem-solving in a particular country.

2. Understanding: comparing public policies can help improve understanding of how government institutions operate within their environment, and suggest possibilities for improvement.

3. Interdependence: the interdependence of nations- as reflected in international agreements, regional politicoeconomic groupings, bilateral treaties and collaboration - is constantly increasing. Accordingly, problems that occur in one country can spill over into other countries more easily and rapidly today than at any other time in history. Similarly, policies adopted in one country often have important implications for others. In other words, knowledge about what has occurred in other countries can help a country prepare for new challenges of its own.

However, any comparative study has methodological limitations. The main limitations of this type of study are as follows.

• Comparability of measurements: Finding truly comparable measurements can be difficult if, for instance, the terminology used in one country does not have an exact equivalent in another country.

• Identifying individual attributes: Certain system attributes- such as the level of development and the influence of public-interest groups- often occur in combination. Disentangling the different factors for the purposes of a study can be problematic. Moreover, each comparative study often involves only a small number of countries. Typically, there are too few cases to permit clear separation of one attribute from another. Consequently, there are not enough national cases available to allow researchers to keep other factors constant while varying only the single factor being tested. Observation under ceteris paribus (“all other things being equal”) conditions is impractical or completely impossible.

• System uniqueness: Every system feature is part of a particular, unique combination of contextual factors. However, since every context is different, comparisons cannot easily be made.

• Causal relationship: Because of the impossibility of isolating factors within a system and its context, it is difficult to draw a rigorous causal relationship between one factor and another. It is therefore not possible to conclude that a particular factor will always lead to the same result in a different country.

• Dynamic nature of system: Systems change over time. However, the comparison is made at a particular point in time. Conclusions about states of development drawn from a comparative analysis of a certain set of countries should not be considered definitive. The value of comparative study lies in the derivation of generic conclusions from the analysis to facilitate learning for system improvement, rather than in any rigid ranking.