Section 631 makes recording telephone conversations illegal without consent. Section 632 makes recording private conversations illegal without consent. Both go on to state: "Except as proof in an action or prosecution for violation of this section, no evidence obtained as a result of eavesdropping upon or recording a confidential communication in violation of this section shall be admissible in any judicial, administrative, legislative, or other proceeding." Whether these sections apply to recorded private conversations that are not communicated by telephone or cell phones is not clear.
It’s my understanding that Sterling had his conversations recorded because he was having memory problems and also wanted his words recorded for his memoirs.