No full democracies score below the CPI average, and fewer than ten countries classified as hybrid regimes or authoritarian regimes score above the CPI average. To account for the effect that development and economic growth have on the relationship between corruption and democracy, we have computed the effects of corruption on the level of democracy, controlling for GDP per capita as well as human development, which includes economic growth, the quality of education and healthcare. Both models show a strong and statistically significant effect of corruption on democracy.

The statistical models predict that a decline of one point in the CPI is associated with a decline of circa 0.6 points in the level of democracy, as measured by the Freedom House aggregate political and civil rights score. Similarly, using the Economist Intelligence Unit Democracy Index, which ranges on a scale of one to 10, one being extremely authoritarian and 10 being a perfectly full democracy, we observe that a 10-point decline in the CPI is associated with a decline of approximately 0.5-points in the Democracy Index score. These models are very simple and not sufficient to explain whether corruption leads to democratic decline or whether democratic decline leads to more corruption, however they are indicative of the very strong association between the two variables.*

While not attempting to solve the dilemma on whether democratic consolidation requires control of corruption first or whether control of corruption requires democratic consolidation, past and present examples clearly show how corrupt leaders have undermined democratic institutions in order to protect themselves from prosecution and to keep stealing state resources.

If we look at the newly democratised countries which have declined or faltered in their quality of democracy (31 in total), we see that practically all of them have high levels of public sector corruption. With the exception of Georgia, all the other 30 countries score below the average in this edition of the CPI. While not attempting to solve the dilemma on whether democratic consolidation requires control of corruption first or whether control of corruption requires democratic consolidation, past and present examples clearly show how corrupt leaders have undermined democratic institutions in order to protect themselves from prosecution and to keep stealing state resources.

When looking at the opposite direction of this relationship, namely the question on whether democracy is a necessary condition in the fight against corruption, the academic literature is entirely split (here and here). CPI 2018 data also shows that some authoritarian regimes are performing well in terms of control of corruption. However, many of the autocracies which are able to control corruption to a satisfactory degree share high levels of human development and efficient state control. Perhaps more importantly, in the long term this high performance of authoritarian regimes on the CPI may be unstable as top-down and non-democratic anti-corruption policies rely on the continued political will of the regime to combat corruption. If and when there is a regime change, these countries can be left without the necessary institutions and mechanisms required to continue enforcing control of corruption.