legal ground
Article 33 of the Criminal Procedure Law of People's Republic of China (PRC)
A criminal suspect or defendant may entrust one or two persons as defenders in addition to exercising their right of defense. The following persons may be entrusted as defenders:
(1) lawyers;
(2) A person recommended by a people's organization or the unit to which the criminal suspect or defendant belongs;
(3) Guardians, relatives and friends of criminal suspects and defendants. A person who has been sentenced to punishment according to law or deprived of or restricted personal freedom shall not act as a defender. A person who has been dismissed from public office or has his lawyer's or notary's practice certificate revoked may not act as a defender, except the guardian or near relative of the criminal suspect or defendant.
Article 34
A criminal suspect has the right to entrust a defender from the day when he is interrogated for the first time by the investigation organ or takes compulsory measures; During the investigation, only lawyers can be entrusted as defenders.