Interrogatory or subpoena on a witness

On Law StackExchange a litigant in pro per outlined the following scenario. Unfortunately his post got censored there, that being the fate of many interesting, practical inquiries.

"I have sued a California mobile-home park LLC for breach of contract and a couple of additional issues. The park manager's failure to properly and lawfully manage the park (which I told the real estate company that owns the park about) are the reason for the suit. She is mentioned as part of the problem, but she is not named as a defendant. Now I need to request discovery from her, but I'm not sure if she is a "party to the action" whom I should give an interrogatory--or a non-party witness whom I would subpoena information from.

Is employee manager a party to the action?"

Regarding your claim of breach of contract, the only entity to be named as defendant is the one with which you entered the contract. Your contract is with the company, whether it is the LLC or --if different-- "the real estate company that owns the park". The "couple of additional issues" are unspecified and therefore cannot be addressed here.

Even if the manager signed your contract, chances are that she acted on behalf of the company. If my understanding of your scenario is accurate, she is not a party. However, discovery on her constitutes discovery on the defendant insofar as she is agent of the company. Your discovery requests should be directed to the defendant, and it is in the details where you should specify what you seek from that employee.

The distinction is somewhat inconsequential, though. The highlight here is that submitting an interrogatory to an adverse witness seems suboptimal. Unless by interrogatory you strictly mean a request for documents, you might want to consider taking her deposition instead.

Depositions are rather expensive, typically in the range of hundreds of dollars. Most of the cost stems from the deposition transcript, which is in terms of price per page. Each page comprises approximately one minute of testimony. But the advantage is that the dynamics of a deposition prevent the adverse witness from conferring with your adversary on how to avoid compromising their legal position and their other interests. In an interrogatory, the adverse witness has ample opportunity to craft answers in a way calculated to be useless to you.

More important is that taking a deposition of a witness also requires dexterity and skill. When thought through in advance, a deposition is more effective for evidencing the witness's inconsistencies or lack of candor.