How Affective Polarization Based on Brexit Identities Biases Citizens When Democratic Norms Are Violated

More voters in the UK now identify as Leaver or Remainer than with one of its political parties. The conflict over the British membership in the EU created a division that cuts across party lines several years after the EU referendum. Do these new political identities generate prejudice akin to party identities? And to what extent to these identities create bias when it comes to violations of civil liberties in the UK? To answer these questions, we test a set of hypotheses derived from a typology of prejudice developed by Allport (1954). The first study was conducted in 2019, i.e. three years after the Brexit referendum. We test a set of six pre-registered online survey experiments with a diverse (non-student) sample of more than 900 respondents recruited on Prolific Academic. The results show that Brexit identities are at least as important for political behaviour as party identities. Moreover, we find that Brexit identities bias citizens’ judgments when it comes to violations of democratic norm. Voters are more forgiving of democratic norm violations (corruption, hateful speech) when conducted by their Brexit in-group and they punish the same violations more harshly when conducted by their Brexit out-group (i.e. by people who do not share their views). We also find that voters discriminate against their Brexit out-group in non-political situations. The second study tests the same hypotheses with equivalent online experiments in the Spring of 2022. We discuss the findings in light of the debate on the disruptive role of affective polarisation and how its behavioural implications cause problems for the functioning of liberal democracies.