Two important lessons of the last dozen years are (1) the government will increase its powers to meet the national security threat fully (because the People demand it), and (2) the enhanced powers will be accompanied by novel systems of review and transparency that seem to those in the Executive branch to be intrusive and antagonistic to the traditional national security mission, but that in the end are key legitimating factors for the expanded authorities.  This was true, I argued in Power and Constraint, about habeas review of GTMO detentions, enhanced congressional and judicial oversight of military commissions, the 2008 amendments to FISA, and greater public transparency and congressional oversight of targeted killing by UAV (a process still in flux).  And it will be true of expanded NSA authorities as the NSA’s vital capabilities become even more important to our security.  In this sense, the Snowden revelations – to the extent that they force NSA to open up, and to get used to greater public scrutiny, and to avoid excesses, and to recalibrate its understanding of the tradeoffs between openness and security – might one day be seen to have paved the way to broader NSA powers.