It might be a bit offtopic but have you already seen this?
https://www.reddit.com/r/Tether/comments/7u3u0c/tether_tokens_on_the_ethereum_blockchain_have/Blacklist & Destroy
The following is for Tether tokens on the Ethereum blockchain only.
The Omni/Bitcoin blockchain Tether tokens function differently, though similarly as well as they can freeze addresses.
Looking through their smart contract source on lines 264 through 299 are the blacklist and destroy functions.
I have excerpted these lines in this pastebin.
Summary
Tether is able to unilaterally blacklist any Ethereum address.
Doing so labels the user as evilUser and all their Tether tokens are designated as dirtyFunds.
Once a user is blacklisted the destroyBlackFunds function can be used on their Tether token balances.
This sets their Tether token balances to 0 and decreases the total supply for the affected Tether tokens.