Pursuant to Clause 2 Article 72 of the Criminal Procedure Code in 2015 stipulating defense counsels as follows:
2. Defense counsels may be:
b) Representatives of persons facing charges;
c) People’s advocates;
d) Legal assistants for charged persons given legal aid.
Pursuant to Clause 4 Article 72 of the Criminal Procedure Code in 2015 stipulating as follows:
4. The following individuals cannot plead:
a) Having engaged in legal proceedings of the lawsuit; or being kindred of persons having engaged in legal procedure of the lawsuit;
b) Having attended the lawsuit as witness testifiers, expert witnesses, valuators, translators, interpreters;
c) Persons sentenced with criminal records sustained, facing criminal prosecution, or sent to mandatory rehabilitation or education centers through administrative measures.
Therefore, if the lawyer is a relative, specifically your younger brother, who is asked to defend your child and does not fall under the cases of people who are not allowed to defend, then he is allowed to defend your child.
Is it permissible to ask a lawyer who is a relative to defend a criminal in Vietnam? - Source: Internet
Pursuant to Clause 2 Article 73 of the Criminal Procedure Code in 2015 stipulating rights and duties of defense counsels as follows:
2. Defense counsels bear these duties:
a) Implement all measures as defined by the laws to clarify facts absolving persons facing charges or mitigating criminal liabilities of suspects and defendants;
b) Provide legal assistance to protect legitimate rights and benefits of persons facing charges;
c) Preserve no right to refuse to defend charged persons whom they have agreed to plead for, if excuses do not rely on force majeure or objective obstacles;
d) Respect the truth and be inhibited to bribe, coerce or incite other people to provide false statements or documents;
dd) Appear as per the Court’s subpoena; or, if defense counsels are appointed according to Point 1, Article 76 of this Law, as per a subpoena by investigation authorities or The procuracy;
e) It is inhibited to disclose investigation secrets perceived during their activities of pleading; or exploit documents transcribed or copied from case files to violate the government’s interests, public benefits, legitimate rights and benefits of authorities and entities;
g) It is forbidden to divulge information on the lawsuit and charged person, which they attain when pleading, unless otherwise agreed by the accused person. It is inhibited to exploit such information to infringe the Government’s interests, public benefits, legitimate rights and benefits of authorities and entities.
Above are obligations of a lawyer in the process of defending a criminal in Vietnam.
Pursuant to Article 74 of the Criminal Procedure Code in 2015 stipulating time of defense counsels' participation in legal proceedings as follows:
Defense counsels engage in legal proceedings upon the prosecution of suspects.
Defense counsels for arrestees and temporary detainees engage in legal proceedings upon the arrestees’ appearance in an office of investigation authorities or units assigned to carry out certain activities of investigation or upon the release of a decision on temporary detainment.
The head of the Procuracy is authorized, when confidentiality of investigations into national security breach is vital, to sanction defense counsels' engagement in legal proceedings after investigations end.
Above is the time when a lawyer participates in the defense in Vietnam.