When a law enforcement officer has stopped a person for temporary questioning pursuant to s. 968.24 and reasonably suspects that he or she or another is in danger of physical injury, the law enforcement officer may search such person for weapons or any instrument or article or substance readily capable of causing physical injury and of a sort not ordinarily carried in public places by law abiding persons. If the law enforcement officer finds such a weapon or instrument, or any other property possession of which the law enforcement officer reasonably believes may constitute the commission of a crime, or which may constitute a threat to his or her safety, the law enforcement officer may take it and keep it until the completion of the questioning, at which time the law enforcement officer shall either return it, if lawfully possessed, or arrest the person so questioned.
Wis. Stat. ยง 968.25
See also the notes to Article I, section 11, of the Wisconsin Constitution.