The Democratic Peace Proposition, which contends that no two democracies have gone to war with each other, has been challenged by scholars who claim that such an argument does not apply to lower forms of conflict. In a series of articles, Margaret Hermann and Charles Kegley argue that democracies often intervene in the internal affairs of other liberal states. But their criteria for case selection and democracy are problematic. In this study, I retest their arguments over a broader time-span, omitting cases of invited intervention, non-state entities, and occupied territories. I also employ new intervention data and a regime-type dataset which accounts for within-year regime changes. I find that liberal countries are less likely to intervene in the affairs of other free states than is expected given the democratic presence in the interstate system. The statistical rarity of such dyadic democratic intervention increases confidence in the applicability of the Democratic Peace to conflicts falling short of war.
Tures, John A. (2001) Democracies as Intervening States: A Critique of Kegley & Hermann, Journal of Peace Research 38 (2): 227–235.