In respect of criminal trial, the court has discretion to decide on the admissibility of the evidence concerned, and the main consideration factors include the evidential value; whether there is prejudicial effect; the identity of the person making the recording as well as the reason and motive; the accusation against the public officer involved; and the nature of the court proceeding seeking the admission of the recording, etc. According to case law, covert recordings are not absolutely inadmissible as evidence.
There is also no general rule precluding all covert recordings from being admitted as evidence. It depends on the circumstances of individual case and there is no hard and fast rule for all such cases.