The Guardian has been calling for a debate about surveillance by the intelligence agencies since Edward Snowden began leaking files which showed the exponential rise in state snooping capabilities.

On Tuesday, the director general of MI5, Andrew Parker, said recent disclosures had harmed Britain's national security, sparking a wave of criticism – mainly from the tabloid press, rightwing media groups and their commentators.

However, significant voices from across the political, cultural and academic spectrum, as well as experts in privacy and security, have acknowledged genuine issues have emerged that need to be discussed. And they have said this discussion is long overdue.

Backed by a growing number of British MPs, and congressional leaders in the US, there is now a clamour for greater oversight of western intelligence agencies and a transparent debate about what the state should be allowed to know. Here are the thoughts of some who have spoken out over the past three months:

The threat to privacy in the digital age

James Clapper, the director of US national intelligence

As loath as I am to give any credit to what's happened here, I think it's clear that some of the conversations this has generated, some of the debate, actually needed to happen.

Mark Zuckerberg, founder of Facebook, after the Guardian revealed details of extensive surveillance programmes in the US and UK

Facebook CEO Mark Zuckerberg delivers a keynote address during the Facebook f8 conference in 2011. Photograph: Justin Sullivan/Getty Images North America

The (US) government response was, 'Oh don't worry, we're not spying on any Americans.' Oh, wonderful: that's really helpful to companies trying to serve people around the world, and that's really going to inspire confidence in American internet companies. I thought that was really bad. We are not at the end of this. I wish that the government would be more proactive about communicating. We are not psyched that we had to sue in order to get this and we take it very seriously.

Tim Berners-Lee, inventor of the world wide web

Unwarranted government surveillance is an intrusion on basic human rights that threatens the very foundations of a democratic society. I call on all web users to demand better legal protection and due process safeguards for the privacy of their online communications, including their right to be informed when someone requests or stores their data. Over the last two decades, the web has become an integral part of our lives. A trace of our use of it can reveal very intimate personal things. A store of this information about each person is a huge liability: whom would you trust to decide when to access it, or even to keep it secure?

Brazil's president, Dilma Rousseff, in a speech to the UN general assembly on 24 September

Brazil's president Dilma Rousseff arrives to meet members of Brazil's football team at Alvorada palace in Brasilia. Photograph: Eraldo Peres/AP

Like many other Latin Americans, I fought against authoritarianism and censorship and I cannot but defend, in an uncompromising fashion, the right to privacy of individuals and the sovereignty of my country. [Rousseff was imprisoned and tortured for her role in a guerrilla movement opposed to Brazil's military dictatorship in the 1970s.] In the absence of the right to privacy, there can be no true freedom of expression and opinion, and therefore no effective democracy. In the absence of the respect for sovereignty, there is no basis for the relationship among nations.

Tom Watson MP, on 19 August

It was Aldous Huxley who said that 'technological progress has merely provided us with more efficient means for going backwards'. And so the Snowden affair reminds us of that, as the ravenous and secret data-crunching machinery of our 'free' liberal democracies are laid bare.

Information Commissioner's Office, on 7 June

There are real issues about the extent to which US law enforcement agencies can access personal data of UK and other European citizens … The ICO has raised this with its European counterparts and the issue is being considered by the European commission, who are in discussions with the US government.

Matthew d'Ancona, Daily Telegraph and Evening Standard columnist, in June

Since the Guardian revealed the existence of the top-secret US surveillance system Prism, there has been a fizzing debate on both sides of the Atlantic about the proprieties of digital data collection. Nothing wrong with that – except that we are having the argument a couple of decades too late and, much worse, framing it in cold war language. The potential scope of the surveillance system said to exist by Snowden is essentially limitless.

John Cusack, film-maker and writer and board member of the Freedom of the Press Foundation

If we want to turn the tide against the national security state, we need to stand with those souls brave enough to confront its crimes.

Jo Glanville, director of English PEN

Following the revelations about the extent to which GCHQ and [America's] National Security Agency have been harvesting our personal data, no citizen can be confident that their communications are private.

Oversight of intelligence agencies and case for reform

Chris Inglis, NSA deputy director

I do think there needs to be more transparency. I do think we have to consider the balance between secrecy and transparency in order to have the public's confidence or [that of] those who stand in the shoes of the public and act on their behalf, say in the Congress. There needs to be greater transparency and we are committed to that.

Lord King, former Tory defence secretary who chaired the cross-party intelligence and security committee:



It is incredible to think how things have changed in the cyber world. Now you have the whole world of Twitter and Facebook, and all the other paraphernalia. Legislation has to keep up to date with all these things and the way people use them. I think it is most important that all the legislation in this area is under regular review.

Dame Stella Rimington, former head of MI5

Author and former MI5 chief Stella Rimington. Photograph: Linda Nylind

It is very important for our intelligence services to have the kind of oversight that people can have confidence in, so that we can be quite sure that in giving them these powers we know that they are being properly supervised and scrutinised in the way they use them. And I think that may mean that now is the time to look again at the oversight of our intelligence services. I'm not sure that Malcolm Rifkind [current Intelligence and Security Committee chair] going on the telly and saying we've scrutinised all this and it's all OK, is enough.

General Michael Hayden, former head of the NSA and CIA

It's clear to me now that in liberal democracies the security services don't get to do what they do without broad public understanding and support. And although the public cannot be briefed on everything, there has to be enough out there so that the majority of the population believe what they are doing is acceptable. My community has to show a lot more leg or we won't get to do any of what we want to do because the public support is so withdrawn that, politically, nobody is going to give us the authorisation.

David Bickford, former legal director of MI5 and MI6

Whether this is based on perception or reality doesn't really matter. As long as government ministers continue to authorise the agencies' eavesdropping, telephone and electronic surveillance, and informant approval, the public will believe that there is an unhealthy seamless relationship between them.

Lord Strasburger, Lib Dem peer

We now know that GCHQ is routinely hoovering up and storing prodigious quantities of the internet communications of millions of innocent people, turning us all from citizens into suspects. As far as I am aware, parliament has not sanctioned this industrial-scale seizure of our private data by the state. Can the minister please tell the House whether this blanket snooping on all of us is authorised by a minister, and if so, which minister sanctioned it, and under which section of which act of parliament?

Douglas Alexander, shadow foreign secretary

Whilst GCHQ do vital work to keep us all safe from harm, it is also vital that they do so with the legal framework set down by parliament and with proper safeguards in place to protect people's privacy. We urged the intelligence and security committee to look into these issues raised by the Guardian and their work is now under way.

Sir David Omand, former GCHQ director

The intelligence and security committee now has to show it can understand the issues [that] advanced intercept technology poses and must be given the expert help to do that. My feeling is that staff in the intelligence agencies would welcome deeper but more informed oversight, not least to protect their reputation.

Cindy Cohn, legal director Electronic Frontier Foundation

The First Amendment protects the freedom to associate and express political views as a group, but the NSA's mass, untargeted collection of Americans' phone records violates that right by giving the government a dramatically detailed picture into our associational ties … who we call, how often we call them, and how long we speak shows the government what groups we belong to or associate with, which political issues concern us, and our religious affiliation. Exposing this information – especially in a massive, untargeted way over a long period of time – violates the constitution and the basic First Amendment tests that have been in place for over 50 years.

Shami Chakrabarti, director of Liberty

It seems our most powerful security agency capitalises on weak legal privacy protections to sell its services to a foreign power. Just as politicians whip up xenophobia and threaten international human rights law, securocrats replace national and parliamentary sovereignty with secret pacts to monitor the globe.

Eric King, head of research at Privacy International

Our intelligence agencies carry out some of the most sensitive and legally complex work in the world. It is shameful that the agreements between the NSA and GCHQ are shrouded in secrecy and this practice must come to an end.

Terrorism and why the Snowden leaks are unlikely to have genuinely affected national security

President Rousseff's speech to the UN

The arguments that the illegal interception of information and data aims at protecting nations against terrorism cannot be sustained. Brazil, Mr President, knows how to protect itself. We reject, fight and do not harbour terrorist groups.

Nigel Inkster, former director of operations and intelligence of MI6, on 12 September

I sense that those most interested in the activities of the NSA and GCHQ have not been told very much they didn't know already or could have inferred.

Peter Swire, former White House chief privacy counsellor, now on President Obama's review panel of the NSA

Due to changing technology, there are indeed specific ways that law enforcement and national security agencies lose specific previous capabilities. These specific losses, however, are more than offset by massive gains. Public debates should recognise that we are truly in a golden age of surveillance.

Bruce Schneier, American cryptographer and specialist in computer security and privacy

Reading the documents leaked so far, I don't see anything that needs to be kept secret. The argument that exposing these documents helps the terrorists doesn't even pass the laugh test; there's nothing here that changes anything any potential terrorist would do or not do.

Sarah Ludford, Lib Dem MEP

We need national parliamentarians to probe the activities of their intelligence services and not be fobbed off by whispers of 'national security, old chaps, you know'.

Poll UK public Photograph: Poll UK public

Clive Stafford Smith, founder and director of Reprieve



It must be said that there is nothing in the Guardian's revelations that has been shown to help terrorists in the least, and Parker did not give a single concrete example to demonstrate this. However, the Guardian has cast light on some worryingly broad snooping by his service. This is a real concern in a democratic society.



Stephen Fry, actor and writer

Privacy and freedom from state intrusion are important for everyone. You can't just scream 'terrorism' and use it as an excuse for Orwellian snooping.

Sunday Times editorial, June 2013

"Most people who use the internet or send emails – and most of us do – are aware that our privacy is at risk. Most are also aware that tapping into electronic communications is a vital tool in the fight against terrorism. A delicate balance between safety and privacy must be arrived at after a full and proper debate in parliament."

How intelligence agencies have compromised the integrity of the internet

Tim Berners-Lee

The original design of the web 24 years ago was for a universal space. We just have to make sure it's not undercut by any large companies or governments trying to use it and get total control.

Editorial in the Economist, September

Any deliberate subversion of cryptographic systems by the NSA is simply a bad idea, and should stop. That would make life harder for the spooks, true, but there are plenty of other more targeted techniques they can use that do not reduce the security of the internet for all of its users, damage the reputation of America's technology industry and leave its government looking untrustworthy and hypocritical.

President Rousseff's speech to the UN

Personal data of citizens was intercepted indiscriminately. Corporate information – often of high economic and even strategic value – was at the centre of espionage activity

Professor Ross Anderson, professor in security engineering at the University of Cambridge computer laboratory

Edward Snowden's revelations are now causing something of a crisis in the IT industry. In the past week I've heard of big firms reconsidering plans to spend hundreds of millions on services that would have been hosted in the US, as they start to realise that US agencies might snoop on their data and use it to tip off their competitors.

Christopher Soghoian, principal technologist and senior policy analyst at the American Civil Liberties Union – after the Guardian revealed US and UK were inserting "backdoors" into commercial encryption programmes

Backdoors are fundamentally in conflict with good security. Backdoors expose all users of a backdoored system, not just intelligence agency targets, to heightened risk of data compromise. The encryption technologies that the NSA has exploited to enable its secret dragnet surveillance are the same technologies that protect our most sensitive information, including medical records, financial transactions, and commercial secrets. Even as the NSA demands more powers to invade our privacy in the name of cybersecurity, it is making the internet less secure and exposing us to criminal hacking, foreign espionage, and unlawful surveillance. The NSA's efforts to secretly defeat encryption are recklessly shortsighted.

Democrats and Republicans poll Photograph: Democrats and Republicans poll

Stephanie Pell, a former prosecutor at the US department of justice

[An] encrypted communications system with a lawful interception backdoor is far more likely to result in the catastrophic loss of communications confidentiality than a system that never has access to the unencrypted communications of its users.

Nick Pickles, Big Brother Watch

The revelations call into question the integrity of cloud services that are used by millions of non-US citizens every day, while setting a dangerous precedent that less democratic regimes around the world may rush to copy. How many members of parliament, business leaders and key figures use US-based services that may have been compromised? Surveillance without suspicion is an affront to a free society and it is essential that we get to the bottom of [what] the NSA and US government has being doing and how British citizens may have seen their privacy compromised on a vast scale.

Joseph Lorenzo Hall, Center for Democracy & Technology

These revelations demonstrate a fundamental attack on the way the internet works. In an era in which businesses, as well as the average consumer, trust secure networks and technologies for sensitive transactions and private communications online, it's incredibly destructive for the NSA to add flaws to such critical infrastructure. The NSA seems to be operating on the fantastically naive assumption that any vulnerabilities it builds into core internet technologies can only be exploited by itself and its global partners. The NSA simply should not be building vulnerabilities into the fundamental tools that we all rely upon to protect our private information.

Jimmy Wales, Wikipedia co-founder

Jimmy Wales, co-founder of Wikipedia. Photograph: Felix Clay

It's pretty astonishing, I think most people would say … I think it's a serious issue and politically it's going to be a serious issue for Obama simply because he did make a lot of positive noises about not doing this kind of thing, or cutting back on it, or being more transparent about it … What I would forecast in the long run is that more and more and more services online are going to go to encryption, not just to stop the government snooping on people, but just for basic security. There's this reluctance on the part of governments to approve that, because they want to snoop on what people are doing.

Edward Felten, professor of computer science, Princeton University, in Nature magazine on 8 October

There was a sense of certain lines that NSA wouldn't cross; and now we're not so sure about that.

Profs Kenneth Paterson, Mark Ryan, Peter Ryan, Vladimiro Sassone, Steve Schneider, Nigel Smart; and Drs Eerke Bolten, George Danezis, Jens Groth, Feng Hao, UK security researchers

One of the prime missions of the security services is to protect citizens and corporations from cyberattack. By weakening cryptographic standards, in as yet undisclosed ways, and by inserting weaknesses into products which we all rely on to secure critical infrastructure, we believe that the agencies have been acting against the interests of the public that they are meant to serve.

Phil Zimmermann, inventor of Pretty Good Privacy cryptography system



We need to pull all our levers – vote, open source, advocacy and economic pressure all around and need to make people care about this. Change isn't going to be large and immediate, but even incremental steps are important.

Zachary Graves, director of digital marketing and policy analyst, R Street Institute

E-commerce relies on data encryption for everything from secure credit card transactions to protecting trade secrets. The NSA's seemingly limitless ability to crack encryption has not only put the privacy of private citizens in danger, it also threatens to shake the foundations of online business.

Rainey Reitman, Electronic Frontier Foundation:

The NSA's overreaching surveillance is creating a climate of fear and chilling free speech. Its addiction to secrecy makes real accountability impossible.

In defence of whistleblowers

Nicolas Maduro, Venezuela's president, in a 6 July independence day speech in which he offered Snowden asylum

"He is a young man who has told the truth, in the spirit of rebellion, about the United States spying on the whole world."

Hugo Rifkind, Times columnist

America would not now be concerned about digital surveillance, even to the vague, diffident degree that it is, were it not for the whistle that Mr Snowden blew. Why, bluntly, is any of this stuff secret at all? I'd rather the west claimed the moral high ground by hacking and bugging less, especially at home, and just dealt with the consequences.

US investigative journalist Seymour Hersh

[Edward Snowden] changed the whole nature of the debate … he changed the whole ballgame. Editors love documents. Chicken-shit editors who wouldn't touch stories like that, they love documents, so he changed the whole ball game.

In defence of public interest journalism

US voters poll Photograph: US voters poll

A letter to David Cameron from editors following the detention of David Miranda – partner of Guardian journalist Glenn Greenwald – and demands for the Guardian to destroy the Snowden files (Bo Lidegaard, Politiken, Denmark; Peter Wolodarski, Dagens Nyheter, Sweden; Hilde Haugsgjerd, Aftenposten, Norway; Riikka Venäläinen, Helsingin Sanomat, Finland)

Events in Great Britain over the past week give rise to deep concern. We may differ on where to draw the line and strike the right balance, but we should not differ in our determination to protect an open debate about these essential questions. We are surprised by the recent acts by officials of your government against our colleagues at the Guardian and deeply concerned that a stout defender of democracy and free debate such as the United Kingdom uses anti-terror legislation in order to legalise what amounts to harassment of both the paper and individuals associated with it. Moreover, it is deeply disturbing that the police have now announced a criminal investigation. We hope this is not to be seen as a step against journalists doing journalism. The implication of these acts may have ramifications far beyond the borders of the UK, undermining the position of the free press throughout the world.

Yvette Cooper, shadow home secretary, following the arrest of Miranda

Any suggestion that terror powers are being misused must be investigated and clarified urgently. The public support for these powers must not be endangered by a perception of misuse. Public confidence in security powers depends on them being used proportionately within the law, and also on having independent checks and balances in place to prevent misuse.

David Davis MP, on Miranda's detention

This is absolutely not solely an operational matter for the police. This relates directly to press freedom and directly to our adherence to the rule of law. I'm afraid you cannot shove this one under the carpet on the basis of national security … The truth is there is too much of a habit in Britain of using terrorism law as a catch-all … The 2000 act was not designed, and certainly not presented, as a mechanism for trawling through people's private information when they passed through Heathrow between two other non-enemy countries.

Michelle Stainstreet, general secretary of the National Union of Journalists

The shocking detention of David Miranda for the crime of being the partner of a respected investigative journalist points to the growing abuse of so-called anti-terror laws in the UK … This is not an isolated problem. The NUJ believes journalists are coming under more scrutiny and surveillance … simply for doing their jobs.

Kirsty Hughes, chief executive of Index on Censorship



Snooping and surveillance on this scale is not only an invasion of privacy, it also undermines the basis of democracy and free speech.

The World Association of Newspapers and News Publishers (WAN-IFRA) following arrest of Miranda and UK government demands to destroy files from Edward Snowden

WAN-IFRA calls on democratic governments to recognise that acts of intimidation and surveillance against the press risk undermining the fabric of transparent, accountable governance.

Thorbjørn Jagland, secretary general, the Council of Europe, the continent's top human rights international organisation, on Miranda and the destruction of the files

These measures … may have a potentially chilling effect on journalists' freedom of expression as guaranteed by article 10 of the European convention on human rights.

Tawanda Hondora, deputy director of law and policy at Amnesty International

Insisting that the Guardian destroy information received from a whistleblower is a sinister turn of events. This is an example of the government trying to undermine press freedoms. It also seriously undermines the right of the public to know what governments do with their personal and private information. If confirmed, these actions expose the UK's hypocrisy as it pushes for freedom of expression overseas. The UK government must explain its actions and publicly affirm its commitment to the rule of law, freedom of expression and the independence of the media. They should initiate an inquiry into who ordered this action against the Guardian. Using strong-arm tactics to try to silence media outlets and reports that divulge information relating to Prism and other surveillance efforts, is clearly against the public interest.

Digital imperialism: international reaction to the US/UK surveillance programmes

The Turkish foreign ministry responding to revelations GCHQ had targeted the country's finance minister during a G20 economics meeting hosted in London in September 2009

The allegations in the Guardian are very worrying … If these allegations are true, this is going to be scandalous for the UK. At a time when international co-operation depends on mutual trust, respect and transparency, such behaviour by an allied country is unacceptable.



A spokesman for the South African foreign ministry, which was a target of a GCHQ hacking operation in 2005

We do not yet have the full benefit of details reported on but in principle we would condemn the abuse of privacy and basic human rights, particularly if it emanates from those who claim to be democrats.

President Rousseff's speech to the UN

Brazilian diplomatic missions, among them the permanent mission to the UN and the office of the president of the republic itself, had their communications intercepted. Tampering in such a manner in the affairs of other countries is a breach of international law and is an affront of the principles that must guide the relations among them, especially among friendly nations. A sovereign nation can never establish itself to the detriment of another sovereign nation. The right to safety of citizens of one country can never be guaranteed by violating fundamental human rights of citizens of another country … The time is ripe to create the conditions to prevent cyberspace from being used as a weapon of war, through espionage, sabotage and attacks against systems and infrastructure of other countries.

Luiz Inácio Lula da Silva, former president of Brazil, after revelations that the NSA had spied on various countries, including allies, in a 6 September interview with the Hindu



The president of the United States should apologise to the world … Now, each country needs to take much more seriously the issue of sovereignty in the area of communication.

Rafael Correa, president of Ecuador, in a 26 June online statement in response to US media criticism of Ecuador for considering asylum for Snowden

[The US media have] managed to focus attention on Snowden and on the 'wicked' countries that 'support' him, making us forget the terrible things against the US people and the whole world that he denounced … The world order isn't only unjust, it's immoral.

Evo Morales, president of Bolivia, speaking on 14 July after learning of NSA hacking at a Mercosur regional summit



Those US intelligence agents have accessed the emails of our most senior authorities in Bolivia … It was recommended to me that I not use email, and I've followed suit and shut it down.

Cristina Fernández de Kirchner, president of Argentina, in a speech at the UN on 6 August

Precisely one of the most distinct reasons for the fall of this [Berlin] wall was firstly that citizens from the other side wanted to live in freedom, they wanted to live without being watched." Fernández also used the speech to call for "establishment of regulations of a global nature to ensure the sovereignty of states and the privacy of citizens in the world.

Martin Schulz, president of European parliament

I am deeply worried and shocked about the allegations of US authorities spying on EU offices. If the allegations prove to be true, it would be an extremely serious matter which will have a severe impact on EU-US relations.

French president, François Hollande