A number of remarkable things have happened this week in the continuing fallout over Edward Snowden's dossier of revelations about mass surveillance. The past two days have seen more disclosures – this time in the Washington Post. The two chiefs of the US National Security Agency are, it has been confirmed, to quit. In the UK, the government has conceded for the first time that the revelations do, indeed, raise wider concerns about the balance between privacy and security which Westminster should consider. In the same breath the prime minister has encouraged parliament to investigate this newspaper for publishing the facts that make any debate possible.

The Washington Post's latest two articles make fascinating reading. One reveals the NSA's extensive involvement in the US's targeted killing drone programme. Another shows how the NSA is harvesting hundreds of millions of individuals' address books at a rate of anything up to 250m a year. Both are valuable contributions to the public's knowledge. They came as Reuters reported that the coming departure of NSA director Keith Alexander and his civilian deputy could give President Obama the chance to reshape the eavesdropping agency.

In America the debate is on the move. There are currently three bills before Congress proposing reforms to the limits and oversight of surveillance. One of them is drafted (with bi-partisan support) by the conservative Republican author of the Patriot Act, Congressman Jim Sensenbrenner, who was appalled to learn – through newspapers, not any form of oversight – about how his legislation was actually being applied. He says he plans "to put [the NSA's] metadata programme out of business".

There are practically no voices in Congress calling for the Washington Post or New York Times to be investigated. It is simply not an issue – just as prior restraint on publication would be unimaginable in the US. The former general counsel of the NSA, Stewart Baker, expressed it thus in a recent debate in New York: "Snowden violated the law, but once he's given it to the reporters, the reporters are protected." It would be unthinkable for a president to suggest that the NYT should be investigated by Congress under the rubric of "counter-terrorism". This current administration has a poor record in regard to aggressively prosecuting whistleblowers, but it is virtually unheard of for espionage legislation to be deployed against reporters. American lawmakers do not confuse terrorism with journalism. Congress does still act as a check on the executive.

In the UK, events are being played out against a backdrop in which politicians are proposing a form of regulation involving the medieval instrument of a royal charter – a form of backdoor legislation cooked up, not (as in popular legend) by Ed Miliband over late-night pizzas, but by the Cameron government itself. We will return to the subject of the post-Leveson debate on another occasion. But the burden of proof over press regulation now shifts. For nearly two years the press was required to demonstrate it could set up its own independent regulator (a task not yet complete). Now the boot is on the other foot: politicians must show they understand the meaning of an unfettered press free to report on matters of high public importance. It's not clear they do.

It is, at least, welcome that the intelligence and security committee has now conceded that the debate that journalism has provoked is a necessary one. The committee has announced it is to take evidence on the vital wider issues raised by the Snowden material. There are, of course, active questions about how effective or independent the ISC has itself proved. So this exercise will also involve yet another burden of proof. The committee has to demonstrate it is not (to borrow a phrase) "marking its own homework" but genuinely hosting an open and long overdue discussion about the difficult balance any democracy has to strike between security, privacy and liberty.