Police will continue using laser guns to detect speeding offences as the recent controversy over a case was down to poor evidence gathering rather than an inaccurate laser reading.

Secretary for Justice Wong Yan Lung assured the Legislative Council today the courts accept the accuracy of laser guns as independent experts have confirmed the devices' precision.

The Department of Justice has reviewed the evidence of the case in question and amended the summons. It said the evidence given by the police officer operating the laser gun used to detect the accused's speed was weak. The officer made mistakes about the offence location and wrongly recorded the test distance as 50 metres instead of 60.

The prosecution and defence agreed to amend the summons and the defendant has been fined and had three licence points deducted.

"The defendant was prosecuted in accordance with the usual practice of dealing with speeding offences," Mr Wong said.

"The decision to amend the contents of the summons was completely based on the evidence's quality unfolded in court, without considering the defendant's identity or status."