In April, stablecoin issuer Tether froze $44.7 million in USDT at the request of Bulgarian police. Now, a company is suing to get it back. Riverstone Consultancy Inc. a firm based in Houston, Texas, has accused Tether of illegally freezing the tokens. Riverstone has missed out on unnamed investment opportunities as a result, according to the lawsuit. The lawsuit casts a spotlight on an issue facing centralized stablecoin issuers: how quickly should they honour law enforcement requests when crypto transa ...