Wis. Stat. § 968.11: Scope of search incident to lawful arrest.

When a lawful arrest is made, a law enforcement officer may reasonably search the person arrested and an area within such person’s immediate presence for the purpose of:

(1) Protecting the officer from attack;

(2) Preventing the person from escaping;

(3) Discovering and seizing the fruits of the crime; or

(4) Discovering and seizing any instruments, articles or things which may have been used in the commission of, or which may constitute evidence of, the offense.