The answer is “yes”.
With a few exceptions, employees are contractually obligated to follow any lawful and reasonable direction issued to them by their employer and a failure to do so can have disciplinary consequences for the employee.
However, to be a direction, the language used must be directive.
I know that sounds kind of obvious.
However, I often advise employer clients who want to take disciplinary action against an employee for not doing what they wanted them to, but the language the client used was discretionary – “I invite”…”when you have a moment”….” it would be great if you could”…:” I advise you not to…”.
In those situations, my advice is that if you have asked an employee to do something and they are resisting, first seek to understand why they are resisting.
There might be a good and sensible reason that can be addressed.
If not, then your language needs to be firmed up.
If the resistance is serious, then a direction should be issued in writing – to avoid evidentiary issues down the track – and be in unambiguously directive terms.
If it’s getting really serious, the written direction should include a warning about the disciplinary consequences of non-compliance.
Do all that and you will be in a strong and defensible position to take disciplinary action if you are dealing with a truly recalcitrant employee.