The FBI may have overstepped its bounds (again) and acted outside what was made legally permissible by a 2008 Justice Department memo when it asked Twitter to provide information about certain account holders. Twitter received the data requests by way of two national security letters (NSLs) that were served, one in 2015 and the other in 2016,

Source: Hot Hardware – Twitter Discloses Warrantless, Potentially Unconstitutional And Illegal FBI Data Requests