There is a new 'no touch smart phone in car by driver' law coming out soon in the UK, so will have to watch using smart phone with sat nav app on the move.
My wife as a passenger just keeps her smart phone by her side, set on sat nav while we are in my car, and as a passenger she should be allowed to touch it, as long as I do not (as driver). Though hands free systems are fine to use.
Its definitely going to be an iffy law trying to explain to a police officer the reason you are using a smart phone in a car at all, but its seems its going to be down to a policeman spotting you, the driver, touching a phone on the move, and your nicked, and a nasty fine. :crying:
https://www.rac.co.uk/drive/advice/legal/mobile-phone-laws/