IDEX, a self-proclaimed decentralized exchange, announced that it will begin blocking new orders from users with New York IP addresses on Thursday, October 25th. IDEX says that it is a decentralized exchange for trading ERC-20 tokens, which "combines the speed of centralization with the security of blockchain settlement".
If an exchange can be pressured into blocking IP addresses of any state or country, it means that it is not decentralized. In case of IDEX, the exchange is non-custodial - it lets users hold their own private keys without giving custody to the exchange. IDEX is still the authority that submits signed trades to Ethereum, which also gives it the ability of selectively blocking IP addresses. (Source: IDEX)