Why don't some lawyers add the defendant WeChat?

Lawyers don't add the defendant's WeChat because there are some restrictions. Without approval, lawyers are not allowed to contact and meet with defendants and witnesses. Legal personnel will not contact the defendant privately through chat tools such as WeChat. Only when undertaking a case, for the sake of the trust of the parties and avoiding the crisis of trust, they generally do not take the initiative to contact each other without the special requirements of the parties.