United Kingdom
The laws most likely to catch a visitor off guard. What is legal at home can be a serious crime here — each rule links to its official source.
Get alerted when this changesLawLert pings you if United Kingdom's laws change. Free.Get the free appCannabis
Cannabis is illegal in the UK as a Class B drug, including types legal in some US states.
Possession can mean up to 5 years in prison; police can also issue an on-the-spot fine of up to £90.
§ GOV.UKMedications
Some medications approved in the US are controlled substances in the UK and need a licence to bring in; carry them in original labelled packaging with a copy of your prescription.
Mailed prescriptions may be blocked by customs, and controlled drugs without authorisation can lead to seizure or prosecution.
§ US State DeptWeapons
It is illegal to carry most knives in public without good reason, including any lock knife or any folding blade over 3 inches; banned knives (flick, butterfly, zombie) cannot even be brought into the UK.
Carrying a knife illegally can mean up to 4 years in prison and an unlimited fine.
§ GOV.UKCustoms & Cash
You must declare cash of £10,000 or more (or equivalent) when carrying it between Great Britain and any country outside the UK.
Undeclared cash can be seized and you may face a penalty of up to £5,000 to get it back.
§ GOV.UKDriving
Traffic in the UK drives on the LEFT side of the road, the opposite of the US.
Confirm your driver's licence is valid in the UK before driving; if you commit a driving offence with no UK address you can be detained.
§ US State DeptThe drink-drive limit is 80mg of alcohol per 100ml of blood in England, Wales and Northern Ireland, but lower at 50mg per 100ml in Scotland.
Driving over the limit can mean an unlimited fine, a driving ban and up to 6 months in prison.
§ GOV.UK