Indeed, We sent down the Torah, in which was guidance and light. The prophets who submitted [to Allah ] judged by it for the Jews, as did the rabbis and scholars by that with which they were entrusted of the Scripture of Allah, and they were witnesses thereto. So do not fear the people but fear Me, and do not exchange My verses for a small price. And whoever does not judge by what Allah has revealed - then it is those who are the disbelievers. And We ordained for them therein a life for a life, an eye for an eye, a nose for a nose, an ear for an ear, a tooth for a tooth, and for wounds is legal retribution. But whoever gives [up his right as] charity, it is an expiation for him. And whoever does not judge by what Allah has revealed - then it is those who are the wrongdoers.
I'm wondering who this applies to specifically. As far as I'm aware, qisas punishment goes through a Sharia court. So, I would expect it's not your average Joe Muslim who is "judging" in this verse, but rather judges or qadi, or people who are qualified to judge in some way.
However, this might also be interpreted as meaning a kind of "personal judgment", such as a belief that "a life for a life", etc., is fair and just, as ordained by Allah.
Question: Does "whoever does not judge by what Allah has revealed" only apply to judges (qadi)?
I found this tafsir:
... whoever does not show what the Qur'an has shown nor act according to it: (such are wrong-doers) who harm themselves with punishment.
Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
This suggests that qisas might be the "tip of the iceberg", referring to judging by all Muslims in all ways. It's not too clear to me, though.