Does Euripides challenge our sense of justice in Medea and how?

I would argue that he does because he forces us to consider whether vengeance is really the same thing as justice. Most people at some point have probably wanted to carry out revenge on those who've done them harm; it's only natural to feel this way. But once we've had time to cool down and reflect, most of us realize that it's better to deal with such matters through the proper channels.
Medea, of course, doesn't do this. She believes in vengeance with a passion, even if it means killing her own innocent children. Although we may initially sympathize with Medea over her callous treatment at the hands of Jason, there can't be many people who'd try to justify her subsequent actions. But as Medea isn't punished for her actions, and as she's whisked away in a chariot by the sun-god Helios at the end of the play, it's clear that the immortals have a very different idea of what constitutes justice.
This makes us reflect on whether there really is such a thing as timeless, higher justice that transcends our own limited human notions. If indeed there is such a higher form of justice, then on the basis of the gods' protecting Medea from the consequences of her murderous actions, we might like to ask whether it's really all it's cracked up to be.