Wis. Stat. § 241.24
No contract for the future purchase, sale, transfer or delivery of personal property through a board of trade or organized commodity exchange is void when either party thereto intends, in good faith, to perform the same; and an intention on the part of either not to perform any such contract does not invalidate it if the other party in good faith intends to perform the same. No such contract is void because the vendor was not, at the time it was made, the owner of the property contracted to be sold; and in any action by either party for the enforcement of its terms or to recover damages for a breach thereof it is incompetent to show in defense, by any extrinsic evidence, that such contract had any other intent or meaning than it expresses; and it and all collateral contracts, agreements or securities growing out of it or of which they may have formed the consideration in whole or in part are legal and valid. Nothing herein shall be construed to exclude evidence of fraud in the procuring of any such contract as is first mentioned herein, or of any collateral contract, agreement or security growing out of it, or that any such contract was not entered into upon sufficient consideration, or is not supported thereby, or that both parties intended to make a wagering contract.
Wis. Stat. § 241.24