Wis. Stat. § 814.34: Attorney for plaintiff liable for costs.

In any case in which the defendant, at the time of the commencement of the action, may require security for costs the attorney for the plaintiff shall be liable for such costs not exceeding $100, until security therefor is filed, whether such security shall have been required by the defendant or not; but such attorney is relieved from such liability by filing an undertaking as prescribed by s. 814.28, and giving notice thereof.