This example assumes it's running inside of a before business rule, which means that the current object is pre-populated with a GlideRecord corresponding to whichever record was inserted or updated, triggering the business rule to run:

if (current.getValue('active') == 'false') { 
    current.setAbortAction(true); 
} 
if (gs.hasRole('admin')) { 
    current.setAbortAction(false); 
}