When social groups face existential crises or protracted intergroup conflict, they may employ punishment to elicit the conformity of ingroup members. . This is supported by experimental work at the group level, which finds that punishment indeed increases conformity and cohesion. However, observational studies suggests that punishment can also result in marginalized group members switching their allegiance to an outgroup. By limiting individual’s ability to switch group membership, prior experimental work on group behaviour has fallen short of fully investigating how individuals respond to intra-group sanctions. We seek to expand this body of work by introducing the possibility to ‘defect’ in an intergroup conflict setting. We present our experimental design and results from pilot sessions before moving forward with full data collection.