Over the past fifteen years, the international community has increasingly relied upon United Nations mandated mechanisms comprising commissions of inquiry, fact- finding missions, and investigations to help address gross violations of human rights and the often blatant disregard for the rule of law during periods of civil unrest, conflict, and post-conflict contexts. The primary reason for why this approach has been preferred centres upon the fact that achieving accountability through internationally mandated tribunals and prosecutions is not only difficult to realize but further complicated due to realpolitik permeating among relevant international decision- making structures. For example, to activate meaningful judicial accountability at the international level, agreement amongst the highest echelons of the United Nations vis- a- vis a Security Council resolution is required to mandate an accountability mechanism. Indeed, even a referral to the permanent International Criminal Court underpinned by the Rome Statute requires a Security Council referral for non- State parties. The complexity of activating these measures, however, has served to ensure the continuation of numerous protracted armed conflicts – characterized by the perpetration of atrocity crimes, violations of international humanitarian law, and violations and abuses of human rights – to the detriment of millions of civilians worldwide. This contribution finds that the Commissions of Inquiry on Syria and Libya have been able to advance the rule of law and the protection of human rights by investigating and reporting publicly on findings by all parties to these respective conflicts, in particular on atrocity crimes, violations of international humanitarian law, and violations and abuses of human rights perpetrated by non- State actors. Both Commissions have taken similar positions on the application of human rights to non- State actors, in that non- State actors that cannot formally become parties to international human rights treaties must nevertheless respect the fundamental human rights of persons in areas where such actors exercise de facto control. The contribution continues by exploring the roles of the Commissions of Inquiry for Syria and Libya in the general quest for prevention: i.e., can the establishment of these mechanisms deter belligerents from perpetrating abuses of human rights and disregarding the rule of law? The article argues that if UN- mandated mechanisms – including commissions of inquiry, fact- finding missions, and investigations – are well supported, especially when concerned States grant such bodies protected access on the ground, they can significantly act as a deterrent and contribute to the respect for human rights and the rule of law. This may be achieved particularly through their cooperation and sharing with accountability bodies and the documentation and preservation of evidence collected.