1、 Principle of fault liability
 According to Article 91 of the Regulation on the Implementation of the Road Traffic Safety Law, the traffic management department of the public security organ shall determine the responsibility of the parties in the traffic accident according to the role of their behavior in the traffic accident and the severity of their fault.
 This article reflects the "principle of fault liability", that is, the occurrence of a traffic accident must first be caused by the behavior of the party concerned, and there is no liability without behavior; Secondly, consider the effect of the behavior of the parties on the occurrence of traffic accidents; Finally, consider the seriousness of the party's fault.
 2、 Principle of causality
 According to the "Provisions on Road Traffic Accident Handling Procedures", the traffic management department of the public security organ shall determine the responsibility of the party according to the role of the party's behavior in the road traffic accident and the severity of the fault.
 （1） If a road traffic accident is caused by the fault of one party, it shall bear full responsibility;
 （2） If a road traffic accident occurs due to the fault of two or more parties, they shall bear the primary responsibility, equal responsibility and secondary responsibility respectively according to the effect of their actions on the accident and the severity of the fault;
 （3） Each party has no fault that causes road traffic accidents. If it is a traffic accident, neither party is responsible.
 If one party intentionally causes a road traffic accident, the other party shall not be liable.
 This article reflects the "principle of causality". When determining the responsibility for traffic accidents, it is necessary to determine which behaviors play a role in the accident and the extent of their role. In other words, in traffic violations, which behaviors have a direct causal relationship with the consequences of the accident, and only those with a causal relationship will bear legal liability.
 3、 Principle of presumption of fault
 According to Article 61 of the Provisions on Road Traffic Accident Handling Procedures, the party concerned shall bear full responsibility in any of the following circumstances:
 （1） Escaping after a road traffic accident;
 （2） Deliberately destroying or forging the scene or destroying evidence.
 In order to avoid legal liability investigation, if the party abandons the car and escapes or absconds to hide, if there is evidence to prove that other parties are also at fault, the liability may be appropriately mitigated, but if there is evidence to prove that the party who escapes has the situation in Item 2 of Paragraph 1, the liability shall not be mitigated.
 This article reflects the "principle of presumption of fault", that is, under the premise of applying the principle of fault liability, in some special circumstances, it is directly inferred from the fact of damage that the perpetrator is at fault, without the need for the victim to provide evidence to prove it.
 [Legal Basis]
 Article 60 of the Provisions on Road Traffic Accident Handling Procedures The traffic management department of the public security organ shall determine the responsibility of the party according to the role of the party's behavior in the road traffic accident and the severity of the fault.
 （1） If a road traffic accident is caused by the fault of one party, it shall bear full responsibility;
 （2） If a road traffic accident occurs due to the fault of two or more parties, they shall bear the primary responsibility, equal responsibility and secondary responsibility respectively according to the effect of their actions on the accident and the severity of the fault;
 （3） Each party has no fault that causes road traffic accidents. If it is a traffic accident, neither party is responsible.
 If one party intentionally causes a road traffic accident, the other party shall not be liable.