In People v. Diaz (1978) 22 Cal.3d 712, the California Supreme Court explained that "in using the term 'prisoner' the Legislature intended to connote a person who has been booked, incarcerated at the time of his escape, or previously so incarcerated and temporarily in custody outside the confinement facility." (Id. at p. 716.)
Consistent with its prior decision in In re Culver (1968) 69 Cal.2d 898, the court held that the earliest an arrestee may be convicted of prisoner escape is booking. (Diaz, supra, at pp. 716-717.)
As the court explained, while the statute also applies to prisoners who have been "charged with" a felony (subdivision (b)) or misdemeanor (subdivision (a)), the Legislature amended both subdivisions in 1961 to add the words "arrested and booked for" in order to clarify that an arrestee is not "charged" within the meaning of the statute prior to booking. (Id. at p. 717); see also In re Culver, supra, at pp. 904-905 "The statute does not apply until an arrestee has been booked preparatory to incarceration in a jail or other place of confinement and thereby becomes a prisoner within its meaning.
By fixing booking as the time at which an arrestee may commit a felony by escaping, the Legislature has added precision to the requirement of incarceration that is implicit in the term 'prisoner'"; People v. Redmond (1966) 246 Cal.App.2d 852, 861 "The addition of these clarifying words 'arrested and booked' indicates that the Legislature did not intend the word 'charged' to be construed to extend to an arrest without a booking".)