You’ve hit on one of the most important defenses in extradition law. Yes, "dual criminality" essentially means the act must be a criminal offense in both the requesting country and the UK. However, it's rarely as simple as it sounds because prosecutors are very good at re-labelling charges to make them look like "fraud" or "obstruction of justice" to bypass this rule. If you want to see how this is argued in real cases, there is some excellent information on the official website extraditionsolicitors.co.uk They have a lot of experience in deconstructing foreign charges and proving that they don't meet the UK legal threshold for a crime. It’s definitely a technical battle that requires a lawyer who knows how to spot these inconsistencies in the warrant.