Wis. Stat. § 119.50
One who deals with a municipality does so at his or her own risk and may be subject to any provisions of law that might prevent him or her from being paid by a municipality even though the services were rendered. Unless the power to bind the municipality financially has been specifically delegated, the only entity with the statutory authority to contract is the municipality. The statutes do not authorize anyone other than the board to enter into contracts. The board may delegate that authority, but it must do so clearly and specifically. For an MPS employee to have such power, it must be specifically delegated by the board to that employee or class of employees. Holzbauer v. Safway Steel Products, Inc. 2005 WI App 240, 288 Wis. 2d 250, 708 N.W.2d 36, 04-2058.