The Motor Vehicles (Tests) Regulations 1981

2.—(1) Where the vehicle is one which the lighting requirements require to be equipped with a headlamp, the vehicle and each of the headlamps with which it is fitted shall be examined in order to determine whether, if that lamp were to be used to show a light to the front while the vehicle was driven on a road during the hours of darkness, the beam of light emitted therefrom—

(a) is or can be so deflected that it is incapable of causing such dazzle as is mentioned in Regulation 9(2) of the Lighting Regulations, or

(b) can be extinguished by the operation of a device which at the same time causes—

(i) a beam of light to be emitted from that lamp, or

(ii) deflects the beam of light from another lamp, or

(iii) brings into operation another lamp which emits a beam of light,

in such manner that in no case is the beam of light so emitted or deflected capable of causing such dazzle as aforesaid.

(2) For the purpose of the examination of a headlamp in accordance with sub-paragraph (1) the direction of the beam of light which would be emitted from that lamp if it were to be used to show a light to the front in the circumstances specified in sub-paragraph (2) shall be tested either—

(a) in the case of a vehicle in any Class by causing the lamp to show a light and ascertaining what the direction is in relation to the vehicle of the beam of light emitted therefrom by the use of apparatus designed and constructed for the purpose of ascertaining within reasonable limits of precision the direction of the beam of light emitted from such a lamp; or

(b) in the case of vehicle in Class I or II, by placing the vehicle on level or uniformly sloping ground, causing the head lamp to show a light so that the beam of light emitted therefrom is thrown on a screen or wall, and ascertaining what the direction of that beam of light is in relation to the vehicle.