Whether using drones for the "targeted killing" of alleged terrorists, or data-mining the phone records of everyone in America, Barack Obama has a standard response to those who would question his use of these questionable clandestine programmes: "We welcome a debate".
Mr Obama's offer of debate sounds all very liberal and reasonable, but for his frustrated critics on both the liberal Left and libertarian Right the offer is nothing more than a cover for a president who campaigned as a liberal but on national security has ruled as an authoritarian.
If Mr Obama really wanted a debate on drones, or the ethics of dragnet-surveillance of the phone records of all Americans, they ask, why has it taken a series of damaging leaks for his administration even to admit the existence of these programmes, let alone openly debate them?
In the centre, Mr Obama has support from both Republicans and Democrats: the leading members of both parties on the Senate intelligence committee, Dianne Feinstein and Saxby Chambliss, both backed the NSA's use of phone records.
But for those on the liberal Left and libertarian Right these broad assurances that constitutional rights to privacy are being observed are ringing increasingly hollow. In this debate, Mr Obama relies almost entirely on his "credibility" - whether or not we believe him when he says, as he did yesterday, that these programmes have been "scrubbed" and come with "increased safeguards".
Ultimately the US public will be the judge of Mr Obama's credibility and he seemed pretty confident of their support yesterday, citing the layers of judicial and congressional oversight that are applied to these programmes.
But after Watergate and Iran Contra, after the dodgy Iraq war dossiers and extraordinary rendition, and even the recent targeting of Conservative groups by the IRS, the US public could be forgiven for not wanting to take Big Brother's platitudes at face value.
Just three months ago, Senator Ron Wyden, who has campaigned against US government data-mining for years, asked James Clapper, the director of national intelligence a simple question: "Does the NSA collect any type of data at all on millions or hundreds of millions of Americans?" "No, sir", came Mr Clapper's reply - which we now know was a flat-out lie. With an "oversight" like that, Mr Obama's credibility is now under scrutiny like never before.