HKSAR v. AU PAK CHEUNG ALEXANDER

HCMA 107/2015

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

MAGISTRACY APPEAL NO. 107 OF 2015

(ON APPEAL FROM ESCC 4120/2013)

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JUDGMENT

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1.  The Appellant was charged with one charge of Dangerous Driving, contrary to section 37(1) of the Road Traffic Ordinance[1]. He appeared before a Magistrate at the Eastern Magistracy and pleaded not guilty. After trial, the Magistrate convicted him of the offence. He now appeals against the conviction.

PROSCECUTION CASE

2.  The incident took place at Wong Nai Chung Gap Road.  The Appellant drove a car on its upward side.

3.  Police set up a road block near Lamp Post 17154 (hereinafter Lamp Post is called LP).  An observation post was set out at Lamp Post 43297.  Officers at the observation post kept under observation the section of the Road between the observation post and LP 43368.

4.  As stated by the Magistrate, there were two limbs of allegation against the Appellant :

(1)   first limb : the Appellant drove at a very high speed and when he was negotiating a right bend the car crossed the continuous double line separating two lanes of the same direction of traffic; and

(2)   second limb : shortly later he was detected by a laser gun to be driving at the speed of 118 km/h at a section of the road where the speed limit was 50 km/h.

5.  The Magistrate found that the prosecution failed to prove the first limb of allegation but found that the second limb was proved.

6.  In relation to the second limb of allegation, the prosecution relied mainly on the evidence of a police officer who operated the laser gun (PW2) and an expert, Professor Tam Wing-yim (PW4).

DEFENCE CASE

7.  At the trial, the Appellant elected not to give evidence. Two experts were called, each concerning one limb of the allegation.

8.  Dr Clark (DW1) was the expert who gave evidence in relation to the second limb.  In reliance on his opinion by reference to the evidence of PW2 concerning the distance of the car from the observation post, the Defence argued that the detected speed was not reliable evidence against the Appellant.

9.  Suffice to say at this stage that the expert status of both experts was not in dispute.

ISSUES AT THE TRIAL AND FINDINGS OF THE MAGISTRATE

10.  As the conviction was based on the second limb of allegation, I will only focus on the evidence relevant to and issues in connection with this limb.

11.  At the trial, the Defence did not challenge the functioning of the laser gun itself.  The main issue was a narrow one : whether on the whole of the evidence the speed as detected by the laser gun was reliable evidence of the speed of the Appellant’s car, or would it at least be possible that it was not.  As it will be seen, the attack on the reliability was based on a discrepancy of evidence between the laser gun operator and the laser gun reading about the distance from the laser gun to the car.

12.  The Magistrate found the detected speed was reliable evidence.  Further, based on this finding, he found that the Appellant had driven dangerously.

GROUNDS OF APPEAL

13.  The Appellant was represented by Mr Gary Plowman, SC, and Mr Samuel Sung[2], who also represented the Appellant at trial.

14.  They advanced three grounds of appeal :

(1)   The Magistrate erred in finding that PW2 was mistaken in his evidence about the distance of the Appellant’s vehicle from the observation post (LP 43368) when he pulled the trigger of the laser gun, in particular :

(a)   There was no evidential basis for such a finding;

(b)   Having found that the evidence of PW2 was mistaken, he then erred by finding that the Appellant was driving the car at a speed of “at least 110 km/h”; and

(c)   He further erred by rejecting the defence submission that there was a strong possibility the laser beam from the laser gun had come into contact with and been reflected from the road surface at a distance of 131.7 meters;

(2)   The Magistrate erred in finding that the Appellant’s driving fell far below what would be expected of a careful and competent driver; and

(3)   In all the circumstances the conviction is unsafe and unsatisfactory.

RESPONSE OF THE RESPONDENT

15.  The Respondent was represented by Mr Edmond Lee, SADPP, and Mr Leung Yuk Hang, Gary, SPP (Ag)[3].

16.  It was their submission that the Magistrate was justified in finding that PW2 had been mistaken in the distance in question.  As a result, this aspect of his evidence should be disregarded and the speed reading of the laser gun should be given full weight.  Further, on the basis that the Appellant was driving at a grossly excessive speed in the circumstances, they submitted that there was sufficient evidence to support a finding of dangerous driving.

DISCUSSION AND CONSIDERATION

GROUND 1

17.  As said, it was argued that the discrepancy in the distance called into question the reliability of the detected speed as evidence of the speed of the Appellant’s car.  The argument runs this way.

18.  PW2, as mentioned above, was the officer who handled the laser gun at the observation post.  What he had done was the normal practice in operating a laser gun to check the speed of an approaching car.  He issued a beam by pulling the trigger of the laser gun.  To make sure the beam lands on the target, he aimed the red dot which was shown in the sighting scope of the laser gun at the front registration plate of the car.

19.  At the beginning of the operation, there was a measurement of the distance between LP 43368 and the observation post.  The distance was 251.3 meters.  Accuracy of this measurement was not in dispute. 

20.  It was the testimony of PW2 that at about 11:23 p.m., he heard loud sound of exhaust pipe and then saw a private car running towards the observation post from the direction of LP 43368.  He then operated the laser gun to detect the speed of the car by aiming the red dot at its front registration plate.  The laser gun displayed the following information : speed was 118 km/h and distance was 131.7 meters. [4]

21.  When PW2 was cross examined, he said at the time he began to pull the trigger, the car was close to LP 43368, having passed it by around 10 meters.[5] He had only pulled the trigger once.

22.  He maintained this evidence in re-examination.

23.  According to the evidence of PW2, by calculation the car was about 241.3 meters from the observation post.  The distance displayed in the laser gun, however, was 131.7 meters.  It follows that there was a discrepancy of some 109 meters between the evidence of PW2 and the distance reading of the laser gun.

24.  Based essentially on the discrepancy in the evidence of the distance, Mr Plowman, SC, submitted that the speed reading of 118 km/h by the laser gun could not be that of the Appellant’s car.

25.  In this regard, expert evidence as to how speed is detected is relevant.

26.  According to the expert called by the prosecution, Professor Tam, PW4, speed reading of a laser gun is derived from the change of distance of two laser pulses being returned to the laser gun over time.  What the operator has to do is to target the object.  (What PW2 had done was basically what an operator should do.)  This action generates laser pulses that will reflect from the target to the laser gun.  Speed reading is derived from change of distance of two laser pulses returned to the laser gun over time.

27.  PW4 further says that in case a laser beam lands on a road surface instead of the car to be targeted, a beam reflection will also be produced.  Such reflection may scattered and then go forward or backward.  Whether beam goes forward or backward depends on the surface of the road.  The smoother the surface, the more light will be reflected in a forward direction.  Part of the scattered light would travel backward in the incident beam direction, i.e., back to the laser gun, thus generating a speed detection reading.  If the returning pulse is strong enough, it will generate a speed reading corresponding to the movement of the laser pulses moving on the road surface.  He said the slightest movement of the laser gun would cause the laser pulses to move rapidly along the road surface.

28.  In addition, PW4 said laser gun, at least for the model in question, cannot distinguish between motion of the target and movement of the laser gun itself.  Therefore, if the laser gun is panned consistently and smoothly, a reading of speed will be produced even if it is targeted at a stationary object.  He called this phenomenon panning or slip effect. Laser gun operator is not expected to pan over the target during speed detection.  However, he admitted that unintentional panning cannot be totally avoided.

29.  Mr Plowman, SC, submitted, both at the trial and at the appeal, that given the abovesaid discrepancy in the evidence of distance, there was a possibility that the speed detection was not generated from laser beam hit directly on the car which was, according to PW2, some 241 meters away from him but rather on the land surface at the distance of 132 meters.  He pointed out that PW4 could not rule out this possibility.[6]    

30.  He sought to fortify his argument with the evidence of the Defence expert, DW1, who was asked to give his opinion as to the possible reasons for the discrepancy of the distance between PW2’s evidence and the laser gun reading.

31.  In his opinion, there were 3 possibilities :

(1)   Mistake on the part of PW2 as to where the targeted car was;

(2)   The laser gun was faulty; or

(3)   The laser beam was reflected from the road surface.

32.  It was the opinion of DW2 that :

(1)   Taking into account the experience of PW2 and the significant degree of discrepancy (as 100 meters equal to the length of almost a football pitch), he did not think PW2 could be mistaken;

(2)   The laser gun was unlikely to be faulty[7]; and

(3)   There was a strong possibility that PW2 had misdirected the laser beam very slightly and the return signal from the road surface at a distance of 131.7 meters away from the observation post reflected back to the laser gun, in other words, the speed reading did not represent the speed of the Appellant’s car.  He said this was the only explanation he could find which fitted the evidence before the court.

33.  In relation to the third point in his opinion, he said that if the laser gun was tilted down by 0.6 degree, the laser beam would have been returned from the road surface and the operator would have been totally unaware of this.[8] DW1 said when a laser gun operator attempts to target an approaching vehicle, there was at least a chance that he has to tilt the laser gun down to keep the moving car in target.  

34.  Mr Plowman, SC, stressed that this aspect of the evidence had not been challenged by the Prosecution.

35.  DW1 further said, if the laser beam hit the white lines which were the road markings on the road, a strong return signal would be generated.  It was undisputed evidence that there were white lines on that part of the road.

36.  DW1 also said, a beam hitting the surface of the road would generate scattered light which may go forward or backward.  A forward scattered light may hit the number plate of the car and then return to the laser gun.  The speed reading so obtained is not accurate as it is not generated from a direct path between the laser gun and the number plate.[9]

37.  Backward scattered light obviously does not produce an accurate speed reading since it is not a result of a beam hit on the car.

38.  It was his evidence that speed reading produced by a beam hitting the road is not accurate.  No matter it is a result of forward scattered light or backward scattered light.

39.  He stressed that his opinion was not based on theoretical possibility only, the possibility of obtaining a reading off the road surface is both sound in theory and practice.

40.  For these reasons, DW1 gave the opinion that the detected speed reading of 118 km/h was inaccurate and unreliable in relation to the Appellant’s car.

41.  The thrust of the submission of Mr Plowman, SC, is this : PW2 could not be mistaken about the location of the car he spotted, the laser gun was unlikely to be faulty, the most reasonable and / or likely reason for the discrepancy in the distance was that the beam from the laser gun hit on the surface of the road rather than on the Appellant’s car.  The speed detected therefore was not a reliable evidence of the speed of his car.  As a result, the prosecution had not proved beyond reasonable doubt that the speed reading was in fact the speed of the Appellant’s car.  It follows that the foundation of the conviction is not solid.  The conviction is unsafe.

42.  The Magistrate, however, took another view.  He found that PW2 was only mistaken on the distance.

43.  The Magistrate based his finding on the following grounds :

(1)   The evidence which PW2 gave about the distance was only an estimate;

(2)   PW2 made his observation in no easy conditions, as he made his observation at night through the sighting scope of the laser gun, against bright headlights, and at a noisy background;

(3)   Taking into account the reaction time required to pull the trigger, it would be impossible that the car had just moved about ten meters after the officer had first observed it;

(4)   Based on the evidence of PW4, it takes time for one to target a moving vehicle before a successful reading could be obtained.

44.  The finding and reasoning of the Magistrate attracted criticism from Mr Plowman, SC.  The main points he put forward were :

(1)   PW2 did not say his evidence of distance was based on estimate;

(2)   The Magistrate failed to have taken into account, or failed to do so sufficiently, that the discrepancy was as much as a hundred meter or so;

(3)   There is no evidence about mistake on the part of PW2;

(4)   The Magistrate failed to have regard, or failed to do so sufficiently, to the following matters :

(a)   PW2 is an experienced laser gun operator, he has been performing this duty since 2006;

(b)   At the beginning of the operation, PW2 took a photograph at the scene and drew a sketch;

(c)   It was the evidence of PW2 that he was familiar with the place;

(d)   He said, when he first saw the car, it was about 5 meters or so away from LP 43368;

(e)   It was also his evidence that when he pulled the trigger of the laser gun, the targeted car was close to LP 43368 and not at a distance of some 131 meter away from where he was;

(f)   PW2 did not say he had difficulties in observation or that he was making observation in difficult situations;

(g)   In any case, there was lack of, at least insufficient, evidence to support a finding that the witness was making observation in difficult situations;

(h)   As regards reaction time, the Magistrate failed to bear in mind that the evidence was unclear whether, when PW2 first saw the car, it was 5 meters before or after LP 43368;

(i)   There was no evidence from any source as to how much time it would have taken PW2 to pull the trigger;

(j)   If the Magistrate had taken into account the calculation made by Prosecuting Counsel in submission, the calculation was premised upon the car travelling at various hypothetical speed;

(k)   In relation to the delay in obtaining a reading, the Magistrate had misunderstood the evidence.  PW4 said the operator need to hold the trigger for 1/3 of a second to 1 - 2 seconds before a reading is obtained[10]; and

(l)   In any case, there was no evidence as to how much time PW2 had taken to bring the red dot onto the front number plate of the targeted car.

45.  It was submitted that, as the Magistrate erred in finding that PW2 was mistaken, he was not entitled to find that the possibility that the return beam to the laser gun came from the road surface at a distance of 131.7 meters did not exist.

46.  Alternately, even if PW2 was mistaken, it does not follow that the possibility of road surface reflection at a distance of 131.7 meters could not exist.  It was submitted that the Magistrate erred in rejecting this possibility.

47.  Mr Plowman, SC, not only submitted that there was no evidential basis to make a finding that PW2 had been mistaken, he further submitted that the Magistrate had compounded the error by finding that the Appellant was driving at a speed of at least 110 km/h.

48.  The Magistrate made the finding on the following basis.  He said, “even assuming PW2 might have unintentionally panned at the road surface ahead of the Appellant’s car after targeting its front registration place and that sufficient strong laser beams might have managed to return to (the laser gun) directly and / or indirectly from such road surface, I think on the materials and evidence before me that it could safely be allowed for by a larger speed allowance of 8 km/h (i.e. 5 km/h for speed variance and another 3 km/h for panning)”[11].

49.  On this, the Magistrate seemed to have relied on the evidence of a test conducted on 28 August 2013 and 13 January 2014 which provided a 3 km/h speed allowance due to panning.

50.  Mr Plowman, SC, pointed out that PW4 had said he could not be sure whether 20km/h panning speed is the maximum panning speed that this particular laser gun could produce.  The witness further said it all depended on the speed of the operator’s hand.[12] PW4 had remarked that this matter could be complicated.[13]  The Magistrate was criticized to have taken a too simplified interpretation of the evidence of the expert witness.

51.  In the circumstances, Mr Plowman, SC, submitted that the Magistrate erred in finding that the Appellant was driving at a speed of at least 100 km/h.

52.  Counsel for the Respondent, Mr Edmond Lee, submitted that the criticisms raised by Mr Plowman, SC, are not justified and submitted that the Magistrate, who had carefully considered the evidence, was entitled on the evidence to find that PW2 had been mistaken.

53.  Mr Lee stressed that PW2 had no opportunity to measure the distance by any reliable method.  What he said about the distance must have been an estimate of his own, even if he had not expressly said so.

54.  Mr Lee also submitted that, notwithstanding that PW2 had not said he was mistaken, the Magistrate was entitled to apply his experience and common sense to make an assessment, and having assessed the evidence was entitled to make a finding that the witness was mistaken, provided there was evidential basis to do so.

55.  Mr Lee supported the view of the Magistrate that PW2 was making observation in difficult situations.  It did not require the witness to provide the situation with a label of “difficulties”, it was sufficient for him to provide the court with evidence relevant to the situation so that the court could make its judgment.

56.  Mr Lee submitted that it was reasonable for the Magistrate to take into account reaction time.  He made reference to the Road User’s Code which states that for a vehicle travelling at 80 km/h, a thinking distance of 20 meters would be required for an attentive and fast reacting driver to react and start applying the brake.

57.  Mr Lee also submitted that the Magistrate has an accurate understanding of the evidence of PW4 about lag time or delay time and supported his thinking in this aspect.  It was his submission that the Magistrate was entitled to adopt a total allowance of 8 km/h, as it was based on an accurate understanding of the evidence of PW4.

58.  Mr Lee observed that the opinion of DW1 that the speed reading was probably a result of the laser gun obtaining the information from reflection from the road surface was based on the presumption that the discrepancy in distance existed.  As the Magistrate found that PW2 had been mistaken, the discrepancy was removed, thus the basis of the opinion of DW1 no longer existed.

59.  He stressed that the witness did not say the laser gun was faulty.  Indeed the whole case was run on the basis that the laser gun was not faulty.

60.  Further, Mr Lee submitted that DW1 was not entitled to give opinion on whether PW2 had been mistaken as it was purely a factual issue to be resolved solely by the tribunal of facts, in this case the Magistrate.

61.  I agree with Mr Lee that PW2 was only testifying on a distance he estimated, he did not use any equipment to help him to gauge the distance. The Magistrate was also entitled to assess whether PW2’s evidence in this regard should be accepted by considering the whole of the relevant evidence. It cannot be said that there is no evidence about possible mistake on the part of PW2.  Even if PW2 did not expressly say that he was making an observation in difficult situations, the Magistrate was entitled to take into account all the evidence relevant to this aspect.  That said, what appears to be a difficult situation by applying common sense may not be difficult, or not as difficult as ordinary reasonable people may think, to a trained officer.  Here the witness did not say he experienced any difficulty.

62.  I am also of the view that the Magistrate is entitled to take into account matters such as reaction time of the laser gun operator, the time it took for the laser gun to obtain the necessary information for speed detection, and the fact that the car was running at least at a considerable speed towards the witness.

63.  For the last point, Mr Lee submitted that the Magistrate was entitled to take into account that the car was running at a speed of 118 km/h whilst Mr Plowman, SC, said it would be wrong for him to do so.  In the circumstances of the present case, bearing in mind the state of evidence and the issue in question, relying on the detected speed of 118 km/h is like putting the cart before the horse.  That said, it must not be ignored that even for a car running at 50 km/h, the speed limit at that portion of the road, it will have travelled about 14 meters in one second.

64.  Allowance must be given to reaction time although how much it takes for one to react differs between persons and depends on the situation.  PW2 was trained in this sort of operation and it may be reasonable to think that it would not have taken him long to react.  That said, reaction varies on each occasion depending on circumstances. 

65.  The Magistrate pointed out that as it was the evidence of PW2 that when he first saw the car it was 5 meters from LP 43368 and when he pulled the trigger it was 10 meters from it, it was quite impossible for PW2 to react so quickly.  In this regard, Mr Plowman, SC, reminded me that the evidence is unclear as to whether, when PW2 first noticed the car, it was 5 meters before or after LP 43368.

66.  In all the circumstances, I am satisfied that the 10 meter distance as testified by PW2 only represented an estimate and the Magistrate was entitled to find that the car had run further than that from LP 43368 when the witness pulled the trigger. 

67.  In other words, I am of the view that the Magistrate was entitled to base his consideration on the basis that the car had reached a point more than 10 meters from LP 43368 when PW2 pulled the trigger.  In this sense, PW2 may be described as having erred in his evidence.  However, on the evidence I find it hard to accept that PW2 had erred by 100 meters.  In any case, I do not think the error was to the extent that his evidence can be totally disregarded.

68.  What Mr Plowman said, in particular paragraph 44 mentioned in paragraph above, are matters which should not be ignored.

69.  In the circumstances of the present case, what the Magistrate should do is to consider the whole of the evidence, including the discrepancy in the evidence of distance, and decide whether the prosecution was able to prove that the speed displayed in the laser gun must represent the speed of the Appellant’s car, and that it was impossible to be a speed detection resulting from something else.

70.  Mr Lee submitted that as the opinion of DW1 was premised on the distance discrepancy, if PW2 erred in his evidence the discrepancy does not exist and the theory of DW1 will fall.

71.  I do not view the matter this way.  The discrepancy, on the face at least, was of 100 meters.  Even taking into account that it involved a car moving towards the witness, and observation of the witness was in no easy situation, the discrepancy cannot be said to be not substantial.  In the circumstances, DW1 was entitled to suggest a possibility which, if not fanciful, is for the prosecution to disprove.

72.  Possibility of speed detection created by reflection from laser beam hitting on road surface is accepted by expert witnesses called by both the prosecution and the defence although there is variance in their detailed opinion.

73.  As regards the effect of forward scattered pulse, PW4 said it is not as dominant as beam hit directly on the licence plate, forward scattered light is weaker.  He further said, if forward scattered light hit the licence plate of the car and reflect back thereby producing speed detection, the speed detected would not differ much from a result detected from one with laser beam hit directly on the car.  He said, motion due to the shift of the pulses is mainly due to the shift of the vehicle, not the road, so the signal detected by the laser gun would not differ very much from the signal directly shining onto the vehicle.  The largest error indicated in the tests he carried out was 7 kilometers per hour.[14]

74.  Mr Lee brought to my attention that whereas PW4 accepted that he could not rule out that scattered signal from road surface could produce speed detection, the signal has to be strong enough for the laser gun to be detected.  He pointed out that at a site visit test, PW4 found the back scattering light from the road surface were too weak for the laser gun to detect.  PW4 also said that at the test he panned the laser gun both horizontally and vertically, back and forth and no signal from the surface as far as 60 something meters was detected.  He was, however, not using the same laser gun for the test.[15]

75.  In this regard, Mr Plowman, SC, pointed out that the Magistrate had expressly said the effort of Professor Tam to rule out reflection from road surface at 131.7 meters away was not successful as he was not comparing like against like.[16] This finding of the Magistrate has significant effect on the decision of this appeal but is one I have to respect.

76.  At the end, it is the burden of proof and standard of proof that matter.  The prosecution bears the burden of proof and has to prove the offence beyond reasonable doubt.

77.  Having considered the whole of the evidence, in particular having regard to the evidence of PW2 in relation to the location of the car, and the opinion of both experts, I do not find myself able to uphold the conclusion of the Magistrate that the speed reading must be a result of reflection of laser beam hitting the car.

78.  As such, the speed reading of the laser gun cannot be safely relied upon to prove the speed of the car driven by the Appellant. 

79.  The basis on which the Magistrate found the Appellant guilty of the offence of Dangerous Driving is removed.

80.  The only other evidence which is available against the Appellant is that PW2 described that the car was driven in high speed.  Mr Lee fairly conceded that it is not sufficient basis to support a conviction of any offence.  Such evidence is too vague.

81.  PW1 had said the car was moving at a speed of about 100 km/h.  This evidence was rejected by the Magistrate.

GROUND 2

82.  In the circumstances, it is not necessary for me to deal with Ground 2. 

GROUND 3

83.  This ground is substantiated.

CONCLUSION

84.  Having considered this particular set of evidence, I allow the appeal and quash the conviction.