U.K. Brian said:
In Britain most detectorists have liability insurance to allay any worries a farmer or landowner has. Its possible you could be blamed for leaving a gate open leading to a herd of prize cattle getting on a busy road and a mass pile up happening.
My insurance through the F.I.D. (Federation of Independant Detectorists) costs £4, around $6 per YEAR. This covers me for £5 million, $7.5 million dollars.
I can understand where the insurance companies are coming from on this because if you fall down a disused well or a mineshaft and break your back you would take the landowner and his insurers to court.