Set permission to fire or deny FormView ModeChanging event based on role

I have an application that uses Windows Authentication to allow users access to a restricted page.  The page has a selectable gridview that shows a formview when a row is selected.  The FormView allows updates to be made to the row.  I want to limit updating to specific authenticated users.  I think the way to do this is to handle the ModeChanging event on the FormView and deny or permit users to change the mode of the formview to update based on their role.  Is this the best way to do this?  How would I implement it?

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