The article addresses the pressing issue of the illegal detention and sentencing of civilians within the context of the Russian-Ukrainian armed conflict, emphasizing the significant challenges posed by the lack of coherent international legal mechanisms to safeguard human rights. In-depth analysis reveals how this legal vacuum complicates the protection of civilian rights during conflicts, highlighting the specific difficulties in verifying abuses and holding the aggressor state accountable. The study explores the nuanced roles that various international and national organizations play in protecting civilians, particularly focusing on the strategic initiatives led by newly established working groups in Ukraine. These organizations and coalitions are crucial in advocating for and protecting the rights of detained civilians, emphasizing the necessity for international cooperation and robust legal frameworks to address and mitigate such humanitarian crises effectively. The absence of unified international legal standards for the treatment of civilians in conflict zones leads to significant challenges. The International Committee of the Red Cross in Ukraine, for instance, notes numerous complications in the detention processes, which depend heavily on the specifics of the charges and legal statutes applied. The status and rights of civilians detained by occupying forces are not adequately addressed by existing international laws, leading to a gap in legal protections and oversight. One of the major obstacles identified is the difficulty in gathering and verifying evidence related to illegal detentions. The conditions of armed conflict severely restrict access to detention sites, making independent and unbiased investigations almost impossible. This not only hinders the prosecution of the aggressor state but also limits the ability of international bodies to monitor and intervene in such situations. Additionally, the article discusses the strategic use of historical legal principles by the occupying powers, specifically the maxim "nullem crimen, nulla poena sine lege" — no crime and no punishment without pre-established law. This principle is exploited to avoid international accountability, allowing the aggressor to conceal their actions and evade international sanctions and legal repercussions. The Geneva Conventions and their Additional Protocols are examined as the foundational frameworks of international humanitarian law that explicitly prohibit any form of violence against civilians, including hostage-taking. However, the ongoing violations of these laws, particularly by the aggressor state, underscore the challenges of enforcing these international norms. The research highlights the urgent need for comprehensive approaches to address the plight of civilian detainees in conflict zones. This involves enhancing international legal standards and improving the coordination among international bodies to ensure the effective protection of human rights. The creation of working groups under the auspices of the Ukrainian Ombudsman exemplifies proactive measures taken to address these issues, facilitating dialogue and action to safeguard civilian rights and ensure compliance with international humanitarian law. In conclusion, the article calls for a concerted international effort to develop and implement more effective mechanisms to respond to human rights violations in conflict zones. Strengthening the legal and operational frameworks for protecting civilian populations not only restores fundamental human rights but also contributes to the broader goals of peace and justice in international relations. This comprehensive approach is vital for the long-term resolution of conflicts and the protection of vulnerable populations in war-torn regions. Key words: civilian hostages, armed conflicts, international law, human rights, unlawful detentions, international organizations, Ukraine, working group.