Liability insurance
All drones other than CE-marked toys must be insured in accordance with (EC) No 785/2004. That means you need to have third-party liability insurance covering at least 0.75 million SDRs (Special Drawing Rights).
In Norway, all aircraft that weigh less than 500 kg must be insured for at least 750 000 SDR. This is according to regulation Forskrift om minstestørrelser på forsikringssummer for passasjer- og tredjemannsansvaret § 4.
This means that you are required to have liability insurance for your drone since the new regulations define all types of drones and model airplanes as unmanned aircraft.
The requirement for approved insurance under luftfartsloven § 11-2, does not apply to unmanned aircraft weighing less than 250 grams, including payload, and operated in the open category. The insurance requirement also does not apply if the drone is CE-marked as toys in accordance with directive 2009/48/EF. The requirement for insurance is rooted inn regulation Forskrift om ubemannede luftfartøyer (BSL A 7-2) § 6 .
The requirement for insurance is based on the fact that the owner of an aircraft is liable for any damage that may occur under flight conditions, regardless of guilt. This is rooted in air law: luftfartsloven § 11-1.