Observed from the angle of law and economics, the legal reason for credit absence lies in both the lower legal cost of credit loss and the absence of law regulation of credit s right.

The research into the development of eco-tourism should explore the issue of constitutional guarantees at a higher level besides the impact of the specific legal reasons.

Based on various doctrines of causation,this thesis attempts to define causative potency and then compares factual causative potency with legal causative potency in order to analyze the function of causative potency.