Do we? I would say that the obligation of the US government is to follow the goals set in the Constitution as much as possible, until such time as the Constitution is amended or replaced. As much as spying does "provide for the common defence", it is defensible. When the spying alienates allies, it is too much. When the spying forces foreign-held companies to pull out, can it really be said to "promote the general Welfare"?

Why would there be such an obligation for unlimited spying?