Since California is a two party consent state for recording conversations, technically the harasser or the harasser’s defenders (like nonresponsive HR people) could sue the victim of harassment for illegally taping them, and could seek injunctions preventing the victim of harassment from using the illegally created recordings in any legal proceedings related to their harassment charges.
That’s why all the advice to just sue or to just call the EEOC falls flat. There is all too often no substantive proof of the victims’ on-on-one interactions with their harassers, and when there are witnesses, they need to be willing to speak against supervisors. If HR has been directed by high-level executives to protect abusive employees on the supervisory level, they tell the harassment victims verbally that no punitive action will be taken so that the paper trail is limited. It’s just not simple.