A California federal court has authorised the US Internal Revenue Service (IRS) to serve a John Doe summons on the digital currency exchange Kraken, seeking information about all US taxpayers who conducted cryptocurrency transactions worth more than USD20,000 between 2016 and 2020. It follows the IRS' success in obtaining a similar summons in April against cryptocurrency exchange Circle and last week's arrest of an alleged operator accused of running an illicit Bitcoin money-transmitting service that laundered hundreds of millions of dollars of Bitcoin.