Wis. Stat. § 844.10: Private nuisances.

Any fence, hedge or other structure in the nature of a fence unnecessarily exceeding 6 feet in height, maliciously erected or maintained for the purpose of annoying the owners or occupants of adjoining property, shall be deemed a private nuisance. However, nothing herein contained shall limit the right of a municipality to forbid the erection of a fence less than 6 feet in height.