addBlackList Function

addBlackList is the specific smart contract function, most notably in Tether's USDT contract, that an authorized owner address calls to add a wallet to the token's blacklist. After it executes, that wallet can no longer send or receive USDT, though it keeps every other asset it holds.

What it means

The function is restricted with an access-control modifier, usually named something like onlyOwner, so it can only be called by the address Tether designates as the contract owner, not by any arbitrary account, and not automatically by any on-chain condition. Calling it sets a boolean flag against the target address inside the contract's internal storage.

Because the call is a normal transaction, it is publicly visible on-chain: anyone can see when an address was blacklisted and by which owner-controlled transaction, even though the reasoning behind the decision is not published. This transparency is what lets tools like FreezeRadar detect blacklist events as they happen, rather than relying on the issuer to announce them.

Real-world example

Etherscan labels the Tether USDT contract's owner-controlled functions directly in its verified source code, and every addBlackList call shows up as a normal transaction from Tether's owner address, publicly timestamped and traceable back to the affected wallet.

Related terms

• removeBlackList Function
• isBlackListed Function
• Stablecoin Blacklist

In FreezeRadar

FreezeRadar reads the live output of the contract's isBlackListed check and the historical log of addBlackList calls, so a scan reflects the current state, not a cached snapshot.

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