In Wisconsin if a person works 48 hrs or more by thurs. can he be deducted for pay if he takes fri. off? All of his scheduled work is finished.

If you are not present for work on a designated work day then yes, you can be charged for the time, regardless of the time you have put in.

If you are a salaried employee, however, it sets a bad precedent for the company to not reward extra hours but punish absences. Have you spoken to your boss about this?

stevetcg makes a good point in regards to salaried pay as opposed to hourly pay. Are you asking for yourself or for someone else? What type of job is it?