You would be very surprised at what constitutes the welfare of shareholders. Shareholders have sued corporations for failing to take advantage of tax avoidance

You would be very surprised at what constitutes the welfare of shareholders. Shareholders have sued corporations for failing to take advantage of tax avoidance strategies (i.e. the plaintiffs contended that the company paid too much tax thus diminishing the amount available to the shareholders). The palintiffs lost - I'm at my wrong computer so I don't have the cite handy. As long as the directors can show they have made a "good faith" attempt to manage to the benefit of the shareholders then they are covered.