My employer just sent out an email stating managers have the right to inspect electronic personal devices used for work. This includes web access to Office 365 via web browser or app installed on a personal phone or computer. Some related questions belong more on workplace exchange. So here I'm just curious if this is legal? If it is a gray area what are the legal implications of fighting it?
(U.S.) An employer has the right to fire you for any reason (with certain exceptions) or no reason at all. For example, your manager can go say that he is going to fire the first person he sees wearing a red shirt and doing so is legal.
Thus, your employer has the right to fire you if you do not turn over such devices for inspection, unless your jurisdiction has some prohibition against it.
There would be no right of the employer to access the devices because of making such a policy.
Thus it would be highly likely that your employer could fire you for not providing such access. It is also possible (but less likely) that a clever lawyer could come up with some cause of action specific to your jurisdiction if it did.
You give no jurisdiction so I will assume Australia but the general basis should be applicable in most jurisdictions.
It is an implicit condition of an employment contract that the employee must obey the "lawful and reasonable" directions of the employer. There is nothing unlawful in what they propose - if you use a personal device for work then they can inspect it.
So is it reasonable?
Probably - the choice as to if this happens lies with you so there is no compulsion here. If you are unwilling to submit to such inspection you can simply stop using your personal devices for work.