Dehghani spoke on Thursday at a special event marking the International Day against Unilateral Coercive Measures, held at the UN in Geneva.
The event was organized by the Group of Friends in Defense of the Charter of the United Nations, with support from Venezuela, Cuba, China, Russia, North Korea, Iran, Mali, Zimbabwe, Nicaragua, Syria, Bolivia and several other countries.
It coincided with the anniversary of the adoption of the Declaration on the Right to Development on Dec. 4, 1986.
The UN General Assembly designated Dec. 4 as the International Day against Unilateral Coercive Measures in resolution 79/193 adopted on June 16, 2025.
Dehghani condemned unilateral sanctions as tools of collective punishment and violations of the right to development.
He called for strengthening relevant General Assembly resolutions and continuing the mandate of the special rapporteur on the issue.
"Unilateral coercive measures are not only illegitimate due to their hostile and coercive nature, but are also completely illegal under international law," Dehghani said.
"These sanctions often serve as a prelude to the use of force; if they succeed, they paralyze nations, and if they fail, the sanctioning countries usually resort to overt aggression."
"Sanctions in practice function as instruments of collective punishment; they slowly take human lives, weaken societies and trample on fundamental human rights, including the rights to health, food and development," he said.
"What armed conflict destroys in days, sanctions systematically, silently and often irreparably achieve over years."
Dehghani criticized the justification of such measures under the term "rules-based international order", saying it replaces universally agreed principles with selective standards.
He urged all states to refrain from applying, implementing, complying with or intensifying such illegal measures.
He stressed the importance of continuing the independent, evidence-based mandate of the special rapporteur.
Dehghani expressed hope that the next special rapporteur would maintain the same high level of expertise and rigor as the current holder, Alena Douhan.
Meanwhile, other members of the Group of Friends in Defense of the Charter of the United Nations and several developing countries described unilateral sanctions as "crimes against humanity" and flagrant violations of the UN Charter and international law, calling for their immediate termination.