I am a California lawyer and cannot speak for Wisconsin law, but in California, the default amount has been found to be an unenforceable penalty in at least two cases: Sybron Corp. v. Clark Hosp. Supply Corp., 76 Cal. App. 3d 896 (1978), and Greentree Financial Group, Inc. v. Execute Sports, Inc. 163 Cal.App.4th 495 (2008). Here are links to a couple of articles in these cases: Californiahttp://www.gordonrees.com/publications/viewPublication.cfm?contentID=510; http://www.lacba.org/Files/LAL/...