Cal. Civ. Proc. Code § 2025.010

Any party may obtain discovery within the scope delimited by Chapter 2 (commencing with Section 2017.010) and Chapter 3 (commencing with Section 2017.710), and subject to the restrictions set forth in Chapter 5 (commencing with Section 2019.010), by taking in California the oral deposition of any person, including any party to the action. The person deposed may be a natural person, an organization such as a public or private corporation, a partnership, an association, or a governmental agency.