Can we impose a disciplinary day off against an exempt employee?

Q. One of our department managers consistently violates our safety policies. We have written him up before, but that does not seem to get through to him. Our safety consultant has suggested that we give the manager a day off without pay to “send a message.” I am concerned that we may have a problem under wage-and-hour laws—that an employer cannot deduct wages from an “exempt” employee. This manager works long hours, and we do not want to face a claim that we made him a nonexempt employee because of a one-day disciplinary suspension. Your thoughts? ...