@mk In general in the Anglosphere, the national government is prohibited from surveiling people without some sort of evidence that the individual is committing a crime (in the U.S. the fourth Amendment to the constitution requires that there be probable cause, warrants, etc.). But if the U.K. decides to spy on an American in the U.S., then share that data with the U.S., apparently that's fine. So that's the "Five Eyes".