Coercion and Protest: An Empirical Test in Two Democratic States

Theory: The theory of protest under varying levels of coercion forms the context for an investigation of the data on protest coercion in Germany and Northern Ireland for 11 years (1982-92), aggregated weekly. Hypotheses: The standard inverted-U hypothesis is tested against competing unstable (protest and coercion diverge and oscillate); backlash (coercion increases protest); and adaptation (protesters change tactics after coercion) hypotheses. Methods: Three forms of the biological predator-prey model are estimated with twoand three-stage least squares and supplemented with a Bayesian updating test. Results: The predator-prey mechanism fits the German data well, even in a context of low coercion. The results cast doubt on the inverted-U hypothesis, support the backlash hypothesis and strengthen the evidence that protesters adapt. Northern Ireland's terror-based protest and coercion did not conform as well to the predatorprey model, but protesters did adapt in a separate test of Bayesian updating.