Suing Saudi Arabia: What could go wrong?

Fifteen years after the attacks of September 11, the families of victims still want authorization to sue Saudi Arabia -- even though there's no "smoking gun." In this election year, they got what they wanted when bipartisan majorities of Congress yesterday overrode a veto by President Obama. But almost before the voting was over, Republican House Speaker Paul Ryan was among those openly voicing second thoughts. Was the President right after all, warning of unintended consequences for Americans overseas?  Can the new law be changed — once the election is over?