The approach that is taken by Proof of Humanity (and by extension Kleros Court) is to have an adversarial process where anyone can claim to be a unique human &

The approach that is taken by Proof of Humanity (and by extension Kleros Court) is to have an adversarial process where anyone can claim to be a unique human & submit evidence, which can then be vouched or challenged by anyone else registered in the system. A challenge is adjudicated by a "jury" of other registered users. There's an economic component as well: you must make a deposit to create a profile or promote a challenge, which you lose if you lose the adjudication. There's even an ERC standard process for adjudication, ERC 792. Surely not foolproof, but more consistent with the distributed ideals than an oracle. https://www.proofofhumanity.id/ https://www.proofofhumanity.id/ https://blog.kleros.io/proof-of-humanity-an-explainer/ https://blog.kleros.io/proof-of-humanity-an-explainer/