Why should this be Barclays' problem at all, though? Beyond perhaps some objective criteria for reporting certain financial transactions to the authorities that deal with things like fraud or money laundering, why should anyone other than official government departments be responsible for making any judgement or taking any other action here? Let the appropriate government departments take official legal action if they think there's a real case to be made, and let them cover the costs of that. Let banks provide banking services and banking customers use them. It's really not complicated or unfair, until someone makes it so.