You should consult your insurance policy for the definition of an uninsured motorist. You can also check Wisconsin Statutues Ch. 632 for more information. If you are unable to answer your question with a review of the policy and the state statutes, that may be a good time to consult with a lawyer.
You should also beware of potential notice of claim requirements if considering claims against the State of Wisconsin. See Wisconsin Statutes Ch 893.80 - .82. for additional information about notice requirements.