Braking bad: how internal brakes restrain violent tactics in leaderless protests

How do protesters restrain their use of violent tactics in leaderless and decentralized mass protests? While existing research highlights the role of leaders and movement organizations in enforcing nonviolent discipline, we lack understanding of how protester violence is regulated from within protest movements in the absence of centralized leadership. This article addresses this puzzle through a case study of Hong Kong's Anti-Extradition Movement of 2019. Through content and descriptive statistical analysis of LIHKG, an influential online discussion forum widely used by protesters during the movement, I examine the discursive strategies protesters employed to restrain violent escalation through the construction of “internal brakes”—discursive reasonings that aim to establish normative boundaries around the tactical use of violence. In addition to describing the basic characteristics of these internal brakes, I identify four subtypes based on their normative logic: proportionality, conditionality, consequentiality, and moral sanity. By analyzing how these brakes emerged and operated in relation to various forms of protester violence during the movement, I demonstrate that their salience varied depending on contextual factors including the target scope, predictability, and severity of the violence they aimed to restrain. The findings contribute to the contentious politics literature by developing a novel theoretical framework for understanding self-regulation mechanisms in leaderless and decentralized movements that experience tactical radicalization.