  A critical issue for society today is the emergence and decline of democracy
worldwide. It is unclear, however, how democratic features, such as elections
and civil liberties, influence this change. Democracy indices, which are the
standard tool to study this question, are based on the a priori assumption that
improvement in any individual feature strengthens democracy overall. We show
that this assumption does not always hold. We use the V-Dem dataset for a
quantitative study of electoral regimes worldwide during the 20th century. We
find a so-far overlooked trade-off between election quality and civil
liberties. In particular, we identify a threshold in the democratisation
process at which the correlation between election quality and civil liberties
flips from negative to positive. Below this threshold we can thus clearly
separate two kinds of non-democratic regimes: autocracies that govern through
tightly controlled elections and regimes in which citizens are free but under
less certainty -- a distinction that existing democracy indices cannot make. We
discuss the stabilising role of election quality uncovered here in the context
of the recently observed decline in democracy score of long-standing
democracies, so-called `democratic backsliding' or `democratic recession'.
