The Optional Protocol to the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (OPCAT) was established in 2002 to facilitate implementation of the Convention against Torture. Due to its regular visitations and national preventive mechanisms (NPMs), as well as increasing ratifications, the OPCAT has been regarded as a paradigm shift in the human rights arena. This dissertation study attempts to discover if states’ commitment to the OPCAT is a sign of increased commitment to human rights or another empty promise. Empirical analyses of states’ ratification of and compliance with the OPCAT provide evidence questioning the high expectations surrounding the treaty’s ratification. First of all, the treaty terms of the OPCAT do not incur as high costs of commitment as expected. Human rights-violating countries have not been deterred from ratifying the treaty, indicating that they are not particularly concerned with potential costs of international and domestic monitoring. Neither has states’ commitment to the OPCAT functioned as a costly signaling. The cost-based theories are further challenged by empirical findings for regional clustering of commitment. Moreover, states’ compliant behavior suggests that the treaty ratification does not guarantee compliance. Regarding the NPMs, about one-third of states parties have not complied with their obligation to designate or establish NPMs. Although most states parties have allowed the international monitoring body unhindered access to places of detention, institutional loopholes in the OPCAT permit states parties to offset the negative consequences of the international visiting program. About the half of states parties have not requested their reports by the international monitoring body to be publicly released, nor have they responded to their reports. The case of the Philippines illustrates that states’ selective compliance or non-compliance with the OPCAT could undermine its effectiveness in preventing states’ practice of torture. Overall, the treaty’s innovative measures make states’ commitment to the OPCAT more than another empty promise. However, ratification is not automatic proof of states’ increased commitment to human rights. Therefore, the international community is strongly recommended to develop effective strategies encouraging states parties to implement the OPCAT rather than simply praise its increasing membership.