The loyalty duty is the most fundamental obligation of a defense lawyer to his client.It means that the defense lawyer should not only safeguard the client's legitimate interests,but also respect the client's basic willingness.Influenced by the lawyer's identity orientation and the criminal procedure model,the defense lawyer's loyalty duty presents three typical models in comparative law,namely,the“complete loyalty duty”model in the United States,the“incomplete loyalty duty”model in Germany and the“mixed loyalty duty”model in Japan.In the three models,lawyers have different characteristics in respect of valuing the client's willingness,handling the conflicts of interests,withdrawing from the defense,and delimitating the boundaries of practice,while facing different theoretical disputes and practical challenges.The formation of the loyalty duty is not only the embodiment of the defense lawyer's socialization,but also the correction of the unbalanced relationship between clients and defense lawyers.It is the assurance of promoting substantive justice and procedural justice,with realizing the maximum defense effect and promoting the sustainable development of the profession.

In practice,a defense lawyer should not only fulfill the logalty duty,but also undertake the public service duty.This duty belongs to the subjects other than the client with the content of safeguarding the social and public interest.It mainly includes the negative duty of truth,the mainte nance of legal order,the prohibition of undermining the integrity of judicial personnel,and the prevention of serious damage to social and public interests.The loyalty duty and the public service duty constitute the two basic duties of the professional ethics of defense lawyers.In general,the two duties play a role in the lawyer's internal and external relations.In a few circumstances,the public service duty constitutes the boundary or exception of the loyalty duty.

The loyalty duty of a defense lawyer to the client runs through the process of formulating the lawyer's professional ethics,whose realization cannot be separated from the implementation of a series of specific professional ethics.The system of realizing the duty of loyalty consists of several rules.First,the rule for avoiding a conflict of interests.It is the direct embodiment of negative loyalty duty.The type of conflict of interest directly determines the method that lawyers could choose to avoid.Violation of the rule will not only bring personal responsibility,but also lead to procedural legal consequences.Second,the rule for keeping professional secrets.It is the most basic duty of defense lawyers,which only creates exceptions in rare cases.Even in exceptional circumstances,defense lawyers should not assume the duty of reporting.Third,the rule for coordination of defense views.Facing the conflict of defense views between defense lawyers and clients,it is necessary to clarify the negotiation duty of defense lawyers,and setting the corresponding procedural consequences of violating this duty.Fourth,the rule for prudent withdrawal from a defense.At present,there are three main methods to withdraw from a defense in China:negotiated termination of the contract,unilateral refusal of defense,and being ordered to withdraw from the defense.When the defense lawyers try to withdraw from the defense,they should avoid adverse effects on the clients and perform a necessary duty of care.The realization of the loyalty duty depends on the personal practice of the defense lawyer with a series of sys tematic guarantees.In the current judicial practice,some mechanisms need to be improved at present,which mainly includes the prevention and control mechanism of lawyers' practice risk,the relief mechanism of lawyers' right to defend,and the punishment mechanism for violating the loyalty duty.