Legal basis:
"Procedures of Public Security Organs in People's Republic of China (PRC) for Handling Criminal Cases" Article 49 If the public security organs are not allowed to meet, they shall notify the defense lawyers in writing and explain the reasons. After the situation that hinders the investigation or may reveal state secrets disappears, the public security organ shall allow the meeting.
In any of the following circumstances, it is "obstructing investigation" as stipulated in this article:
(a) may destroy or falsify evidence, interfere with witness testimony or collusion;
(2) It may lead to the criminal suspect's self-mutilation, suicide or escape;
(3) It may cause accomplices to evade or obstruct the investigation;
(4) The criminal suspect's family members participate in the crime.