Anticorruption campaigns increasingly involve the criminal prosecution of perpetrators of grand political corruption. While curbing political corruption may be a worthwhile cause it comes with unintended political side-effects, including the destabilization of legislative party systems. Using original datasets on corruption convictions and legislative behavior in Romania’s parliament from 2008 to 2020, we estimate the effects of criminal convictions on legislative party switching. We find that corruption convictions of party leaders and cabinet ministers from one’s party significantly increase the probability of MPs switching to another party. This evidence suggests that anticorruption campaigns are a double-edged sword: criminal convictions of perpetrators of grand corruption may enhance accountability, but they also destabilize party systems by fueling legislative party switching.