Last Friday, Daisy was taking a walk near her residence after dinner. While she was walking on the pavement, Arnold, a successful young businessman, was riding his new electric bicycle on the same pavement at high speed. Unfortunately, Daisy was accidentally knocked down by Arnold's electric bicycle which caused her left arm injured although not serious. Some witnesses quickly called 999 and the ambulance and police arrived later. After the policemen recorded the details of this incident, Arnold was taken to the police station for further investigation.

Now, Daisy wants to claim compensation amount to HK$5,000 from Arnold for her injury. Explain whether the case involves criminal law or civil law. Discuss the characteristics of this kind of law