Appointment Of A Private Advocate By A Public Servant For His Defence

A public servant acting under his public duty was denied orally by his department to provide a panel advocate. The case is upon the department but department held that public servant responsible and denied him to provide advocate. There is no written authority by the department to provide lawyer. Can that public servant engage a private lawyer in this case. If there is any Supreme court or high court judgement on this matter ?Plz advise