People v. B.M. (In re B.M.), 241 Cal. Rptr. 3d 543

Defendant B.M., age 17, entered her sister Sophia’s bedroom angry, grabbed a six‑inch metal "butter knife" from the kitchen, and made several downward/slicing motions toward Sophia’s legs while Sophia was covered by a blanket.
Sophia felt the motions against her blanket and was frightened but sustained no injury; B.M. testified she intended only to scare Sophia and did not stab.
Juvenile wardship petition alleged assault with a deadly weapon under Penal Code § 245(a)(1); the juvenile court sustained the petition.
The Court of Appeal affirmed, concluding the butter knife could have produced great bodily injury and criticizing In re Brandon T. as wrongly decided.
The California Supreme Court granted review to decide whether substantial evidence supported a finding that the butter knife was used as a "deadly weapon."
The Supreme Court reversed the Court of Appeal, holding the evidence was insufficient to show the knife was used in a manner "likely to produce death or great bodily injury."

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the butter knife was a "deadly weapon" under § 245(a)(1) based on how it was used	The Attorney General argued B.M. used the knife in a way capable of and increasing the likelihood of great bodily injury; lack of injury or imperfect skill doesn’t negate deadly‑weapon status	B.M. argued the knife was blunt, used against blanket‑covered legs with only moderate pressure, and could not have been used in a manner likely to cause death or great bodily injury	Reversed: substantial evidence did not show the knife was used in a manner "likely to produce" death or great bodily injury; mere capability or conjecture is insufficient
Proper standard and evidence scope for determining a "deadly weapon"	The AG and Court of Appeal treated "capable of producing" as effectively sufficient and relied on possible alternative uses to infer likelihood	B.M. argued the standard requires proof the actual manner of use was likely to produce death or great bodily injury; speculation about alternative uses is improper	Held: Aguilar requires the object be used in a manner both capable of and likely to produce death or great bodily injury; inquiry must focus on how the object was actually used and consider extent of actual injury or damage to the object, without conjecture

People v. Aguilar, 16 Cal.4th 1023 (establishes that a "deadly weapon" under § 245(a)(1) is an object used in a manner both capable of and likely to produce death or great bodily injury)
In re Brandon T., 191 Cal.App.4th 1491 (butter‑knife facts; held insufficient evidence of deadly‑weapon use where knife failed to cut and broke, producing only minor injury)
People v. Duke, 174 Cal.App.3d 296 (holds inquiry focuses on force actually used, not force that could have been used; rejects speculation about what defendant might have done)
People v. Beasley, 105 Cal.App.4th 1078 (limited injuries from instrument inconsistent with using it as a deadly weapon; evidentiary limits on inferring deadly‑weapon use)