bq. This natural experimental design has provided a unique test of whether international observers can deter election-day fraud, providing causal evidence of how international actors can influence domestic politics. The evidence presented above shows that the presence of international observers depressed the incumbent’s round 1 average vote share by 6 percent in polling stations that were observed. Since the incumbent was only 0.52 percent away from avoiding a round 2 runoff, international observers may have been responsible for triggering a second round of competition.
This is the conclusion of Susan Hyde’s study of the 2003 Armenian election (here, gated). She takes advantage of the fact that international observers were assigned to polling stations approximately randomly.
Paradoxically, however, the presence of international observers during an election seems to encourage opposition parties to boycott. See this paper (gated), by Hyde and Emily Beaulieu. They write:
bq. …international benefits for democratic elections give electoral autocrats the incentive to invite international observers and manipulate elections to minimize international criticism. This increase in “strategic manipulation” has led to changed incentives for opposition political parties, which have the most to lose from a manipulated but internationally certified election. Consequently, international monitors increase boycott probability.
But why would incumbents risk condemnation by manipulating elections in front of international observers? In this paper, Hyde writes:
bq. This article began with an empirical puzzle. Many leaders invite international election observers, cheat in front of them, and face negative consequences as a result. For pseudodemocrats, being caught cheating by international observers can lead to international condemnation, domestic uprising, and an overall reduction in the probability that they will maintain their hold on power. The existence of the norm of election observation explains this puzzle. Without the norm, held and enforced by the international community, the rate of observed elections should have begun decreasing by the end of the 1990s as observers grew better at catching election fraud and more likely to sanction fraudulent elections. Instead, the rate of observed elections continued to increase during this time period, even as the risks associated with inviting increased. All else held equal, one could argue that a number of leaders who invite international election observers would prefer a world without the norm of election observation.
bq. In other issue areas within international relations, compliance with such costly norms has been explained as the result of pressure from activists or powerful states. Election observation, in contrast, was initiated by state leaders to signal a government’s commitment to democratization. As more international benefits were linked to democracy, leaders who were not necessarily committed democrats also had the incentive to invite observers. This repeated behavior resulted in acceptance of election observation as compatible with respect for state sovereignty. As a result of the normalization of election observation, international actors began to punish leaders who did not invite observers and invest in improving election observation technology, thus reinforcing the norm even as compliance with the norm became more costly for pseudodemocrats.
On international observers and, more broadly, how to make democracies “self-enforcing,” see this paper by James Fearon. On election fraud, see this volume, edited by Hyde, Michael Alvarez, and Thad Hall.