In People v. Mercer (1995) 42 Cal.App.4th Supp.1, the court noted section 12020 does not list a "baton," and therefore examined whether the item seized from the defendant was an " 'instrument or weapon of the kind commonly known as a . . . billy.' " (People v. Mercer, supra, 42 Cal.App.4th at p. Supp. 4.) Mercer noted that, in People v. Grubb (1965) 63 Cal.2d 614, the court determined section 12020 was not unconstitutionally vague and permissibly outlawed instruments other than those specifically enumerated in the statute. As explained in Grubb: "Defendant complains that . . . the statute is unconstitutionally vague because a man of common intelligence cannot know if he violates its prohibition in view of its sweeping coverage. The contention runs that the term 'billy' encompasses such ordinary objects as an orthodox baseball bat, a table leg, or a piece of lumber; even though these objects find their most common use in a peaceful and traditionally acceptable way, all of them could be used as weapons of physical violence. We must construe the enactment, however, in the light of the legislative design and purpose. The Legislature obviously sought to condemn weapons common to the criminal's arsenal; it meant as well 'to outlaw instruments which are ordinarily used for criminal and unlawful purposes.' . . .The terms of the statute gain content and definition by reference to this purpose. . . . The Legislature here sought to outlaw the classic instruments of violence and their homemade equivalents; the Legislature sought likewise to outlaw possession of the sometimes-useful object when the attendant circumstances, including the time, place, destination of the possessor, the alteration of the object from standard form, and other relevant facts indicated that the possessor would use the object for a dangerous, not harmless, purpose. Thus we hold that the statute embraces instruments other than those specially created or manufactured for criminal purposes; it specifically includes those objects 'of the kind commonly known as a billy.' The concomitant circumstances may well proclaim the danger of even the innocent-appearing utensil. The Legislature thus decrees as criminal the possession of ordinarily harmless objects when the circumstances of possession demonstrate an immediate atmosphere of danger. Accordingly the statute would encompass the possession of a table leg, in one sense an obviously useful item, when it is detached from the table and carried at night in a 'tough' neighborhood to the scene of a riot. On the other hand the section would not penalize the Little Leaguer at bat in a baseball game." (Id. at 619-621.) As Mercer also noted, in People v. Canales (1936) 12 Cal.App.2d 215, the court (upholding a conviction of possessing "a black jack or billy") explained the "definition (i.e., instruments 'of the kind commonly known as a . . . billy') is purposely broad, for . . . the Legislature did not prohibit the possession of a blackjack as such or a billy as such as it might have done, but instead and very likely with appreciation of the difficulties of nomenclature, forbade ownership of any weapon of that class; the purpose being to outlaw instruments . . . ordinarily used for criminal and unlawful purposes." (Canales, at p. 217.) In Mercer, the court applied Grubb and Canales to an item described as a collapsible baton where the evidence was that the baton was " 'used for the same purpose as a billy which is a striking motion.' " (Mercer, supra, 42 Cal.App.4th at p. Supp. 5.) Although the Mercer defendant claimed the baton was a truck antenna, the arresting officer's report stated that when he saw the object he " 'immediately recognized it as a weapon commonly known as a collapsible baton. The weapon, when extended by a flick of the wrist, is extended and used as a club. I have seen this weapon on several occasions and it is used by police and martial artists as an offensive weapon used to strike.' " (Ibid.) Mercer concluded that, "under the above authorities, possession of such an item is proscribed by section 12020, subdivision (a)." (Ibid.) Indeed, Mercer noted numerous other provisions of the Dangerous Weapon Control Law ( 12000 et seq.) confirmed its interpretation that a baton used for striking purposes was the type of instrument falling within the purview of the prohibitions against "billys." (Mercer, at p. Supp. 6.) In Mercer, the police report showed the defendant was apprehended while apparently leaving the scene of a burglary, and a pat-down search for weapons discovered the collapsible baton. Mercer stated, "even assuming arguendo that the instrument found on appellant's person was not initially meant to be a weapon, the attendant circumstances indicate that the item was to be used as a weapon at the time of arrest." (Mercer, supra, 42 Cal.App.4th at p. Supp. 6.)