In Employment Law cases, a disgruntled employee, anticipating the need to prove some aspect of the case, will secretly record a conversation with an employer.  The employee then sees an attorney, discloses that the recording has been made, and proudly announces that it is proof of the misconduct by the employer. The Plaintiff’s attorney only groans.
Witness the battle of the Penal Code sections. In one corner, Penal Code § 632 prohibits the recording of a confidential communication without the consent of the parties. In the other corner, Penal Code § 632 (c) permits the use of a recording where the communication is made in a public gathering or in other circumstances where confidentiality could not reasonably be expected. 
May a secretly recorded conversation ever be used in a court as evidence? The answer is “sometimes.” If the statement is used for impeachment purposes, exposing that the other party is committing perjury, or something resembling perjury, courts have permitted the criminally procured statement to be admitted. The idea is that the policy against perjury outweighs the policy against secret recordings.
Of course a sticky issue arises where discovery asks for all recordings in the possession or custody of the employee [or employer]. The employer, if it acts quickly, can obtain the identity and fact of the recording, and therefore alert its witnesses to avoid any lying on the witness stand. Further, the employer can use the secret recording as basis to assert an “affirmative defense” cutting off damages [“after-acquired evidence rule”] from the date it discovers that the secret recording was made.  Therefore, the Plaintiff’s attorney should quickly take the deposition of the defense witnesses in the hope that their inconsistencies can be exposed by the secret recording before it is necessary to identify the recording.
In any event, counsel should never participate in a criminal activity of encouraging or condoning the use of a secret recording in the workplace.
See generally Fria v. Superior Court (1988) 203 Cal. App. 3rd 1480 and People v. Crow (1994) 28 Cal. App. 4th 440.  

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