The brutal course of revenge which Medea exacts on Jason may suggest that in the pursuit of revenge, one render any prospect of attaining justice to be void. However in an indirect way, Medea's course of revenge which implicates the lives of innocents, exerts a punishment on her. Ultimately, the fact that Medea is not directly subjected to a punishment for her extreme course of her revenge is attributable to her ancestry - she is the grand-daughter of the Sun-God. This nullifies any suggestion that seeking revenge overthrows the likelihood of justice, as Medea's divine circumstances are an anomaly. Thereby, this outcome of her ploy of revenge is not representative of the outcome which an identical course of revenge would yield for an ordinary citizen in Ancient Greece.
On a superficial and simplistic level, the success of Medea's course of revenge suggests that justice has been attained, as we witness the rightful downfall of Jason.
Jason's betrayal of Medea in the form of his abandonment, results in the breaking of the oath he pledged to Medea and the Gods. Thus, in adherence to the notion of divine justice, that the Gods will exact justice on those who commit unnatural deeds, Jason deserves a calamitous punishment for the breaking of this oath to the Gods and Medea, who "never did him wrong". Through achieving revenge on Jason in the most effective manner possible, via murdering their children and his wife, Medea inflicts this just punishment on Jason.
However, on a more profound level, Medea's immoderate course of revenge instills within the audience a sense that her course of revenge has been essentially counter-productive to achieving true justice. In her pursuit of revenge, Medea murders her innocent children, indicating that she has committed an indisputably barbaric injustice, while seeking to exert...