Unless there’s something going on that I don’t know about, the answer is NO. The legal analysis: The employee is asking for an accommodation for a disability. You’re required to make reasonable accommodations to the point of undue hardship. You’re entitled to request a medical assessment of the employee’s capabilities so you can determine which accommodations to make. The employee is required to cooperate in the accommodation process by providing the requested information–as long as the information is relevant to and no more than necessary to make the assessment. If the employee refuses to cooperate, undue hardship is reached and you don’t have to make accommodations.
Advice: Keep careful records documenting your requests and employee’s failure to provide the info in case you’re challenged in court or arbitration. Hope that helps. Glenn