As part of the EU whole vehicle type approval process, safety standards are prescribed for glazing materials for use in vehicles. These standards cover field of vision and transparency. Provided vehicles are glazed to the required standards, it is not open to individual member states to prohibit their sale or use.
Under the Road Traffic (Construction, Equipment and Use of Vehicles) Regulations 1963, a vehicle must be constructed so that the driver can at all times have such a view of the road and of other traffic on the road as is necessary to enable him to drive safely. The regulations also provide that where a windscreen is fitted to a vehicle, it shall be of a stable substance and fully transparent so that it does not distort the driver's view of objects.