Ken has established a family in Hong Kong. He works very hard to sustain a living. He is employed by a department store as sales and works as part-time taxi driver during night time. One evening while he was driving a passenger to Sai Kung, he was tired and paid no attention to the traffic light. Carelessly he drove across the road when the traffic light had turned green for pedestrians. The road condition was clear at that time and nothing blocked his sight. He knocked down a teenager, Sam who died afterwards. Police investigation revealed no evidence that Sam has breached any traffic rule when he crossed the zebra crossing.

Sams parents wish to claim from Ken based on negligence causing the death of their son. With the assistance of relevant legal cases and principles, explain to Sams parents the concept of duty of care which is essential in establishing negligence.