The implementation of incarceration and the expansion of "prison-centric policy" (or "carceralism") along with the emergence of its detrimental consequences, including the deleterious effects it imposes on the economy, society, and the family, have progressively led "decarceration" to leave its mark on the criminal policy agendas of states. On the other hand, penal transformations are by no means confined to domestic factors within a single country; in this regard, international and human rights instruments, as well as global developments, have also been influential, playing both direct and indirect roles. It is therefore essential to examine the most recent developments in "penal mitigation" as a tool for decarceration, based on these instruments. The research method employed in this study is descriptive-analytical, examining the transformations that have occurred in penal mitigation in furtherance of decarceration, based on the legislator’s latest intent in the Law on Reduction of Ta’zir Imprisonment Penalties (2020), while considering international instruments. Within the corpus of international instruments overseeing penal transformations in the direction of decarceration, the efforts undertaken indicate an attention to the principle of the minimal use of this punishment, attempting to implement it by providing guidelines. Although, for its part, the decarceration policy in Iran, relying on penal mitigation to reduce the penal population, has in certain respects brought about positive developments aligned with these instruments - aiming for the minimal and individualized application of imprisonment and its replacement with other measures - this policy has simultaneously posed challenges for this institution which have been overlooked by the legislator.