>Is this documented anywhere? What's the procedure within USDC to perform this block?

https://etherscan.io/address/0xa0b86991c6218b36c1d19d4a2e9eb...

The smart contract has a "blacklist" function.

Does the proxy implementation pattern used in this contract actually mean that the owner of the corresponding keys can not only block addresses from holding USDC, but actually swap out the entire implementation, e.g. for one implementing transaction or inactivity fees?

Why does it matter? They owe you the money in the first place. If they’re ill-intentioned they can just refuse to redeem your coins, or require that you send them to a new contract with different rules.

There’s no reason credit instruments should be on a blockchain in the first place, given you’re depending on a central party for redemption.

> There’s no reason credit instruments should be on a blockchain in the first place, given you’re depending on a central party for redemption.

Can you elaborate? Say you issue RUNEKs, how do we move them around freely in a digital world with the assumption that you are not required for transfers?

Why don’t you want me to be required for transfers?

You already depend on me for redeeming your coins for USD, so depending on me for transfers doesn’t present any additional risk.

Runek seems more likely to be asking, why pay the very high price of putting a trusted instrument on a trustless blockchain. Which I believe is a fair question.

I'm asking how else can you get the same functionality.

{ blacklist, unBlacklist, updateBlacklister (add), isBlacklist }

Looks like a full API to manage a blacklist and an authorization scheme for adding blacklist administrators.

Oh hm I should of clarified, I meant more like the human procedures to go forth and run the blacklist function, I'm sure the actual code is documented (and it appears to be - nice!), but it doesn't really matter how secure the code is if anyone inside the organization can execute it.

Although having an un-block function is good thinking since it would allow them to reverse course - no bad decision is permanent.