Video used in speed gun case questioned

A local expert has challenged video evidence used in the speeding case of tycoon Peter Lam Kin-ngok, saying flaws it highlighted would not occur if guidelines on the use of laser guns were followed.

The video of British experts testing a laser gun showed the devices could make mistakes if misaligned or the laser beams were reflected.

Tam Wing-yim, a Hong Kong University of Science and Technology laser-gun expert who tests them for police, described the flaws as 'scary' after watching the video in the Legislative Council transport panel yesterday.

'A misalignment like the one shown in the video clip should have been identified by the officer and the laser gun returned for maintenance,' he said.

In the video, a laser gun is pointed at a wall and a reading suggests the wall is moving. Instead, the reading is a result of the officer moving from his initial position. Inaccurate readings were also recorded when the gun was used 400 metres from the target.

'Several tests in the video may have been set up for a certain purpose, but it did not show what happens when the gun is used properly,' Dr Tam said.

He said that in Hong Kong, laser guns were mostly used within 100 metres of their targets. The guns are also returned to the manufacturer for maintenance every six months.