The events of last week involving the Guardian and its reporters have renewed debate and inflamed concern about the age-old dilemma of how to strike the balance between individual liberty and collective security. The coalition made freedom one of its founding principles back in 2010 and many people are looking to us now to prove we meant it.

Liberal Democrats believe government must tread the fine line between liberty and security very carefully, and are not easily persuaded by a government minister asserting: "Just trust me." So now that we are in government, we have been vigilant in ensuring the right decisions are made: scrutinising and challenging the assumptions of security experts, even as we give them our wholehearted support in their aim to keep the public safe.

You may remember the ferocious debate earlier this year between me and the Conservatives on plans to introduce a "snooper's charter", keeping records of everyone's email and internet activity. We looked at the details time and again, and agreed to tackle the issue of how we track IP addresses, but the plan as a whole was a bridge too far.

One point on which both parties have been united is this: seeking to unpick the worst excesses of Labour's authoritarian legislation. From restoring rights to protest, ending the detention of children in immigration cases, scrapping ID cards and limiting some terrorism powers, we have turned the clock back on their biggest mistakes. It has been bizarre to see Yvette Cooper parrot concerns about civil liberties while representing a party hard-wired to trample on those liberties while in office. People are right to ask questions about the detention of David Miranda for nine hours this week. But Cooper voted for powers to detain suspects for 90 days – 2,160 hours. Her outrage is almost comical.

Let me address directly the two specific decisions that have confronted the government this week. I believed at the time, and still do, that it was entirely reasonable for the government to seek to get leaked documents back from the Guardian or have them destroyed. Along with the information the newspaper had published, it had information that put national security and lives at risk. It was right for us to want that information destroyed. The Guardian had decided not to publish this information: not a single sentence was censored from the newspaper as a result of the information being destroyed.

I was not consulted on the plans to detain him before it happened, and I acknowledge the many concerns raised about the use of schedule 7 of the Terrorism Act 2000 for these purposes. There is obviously a material difference between agreeing by mutual consent that files will be destroyed, and forcibly detaining someone. Terrorism powers should be used proportionately. That is why it is immensely important that the independent reviewer of terrorism powers, David Anderson QC, reports rapidly on whether this was a legitimate use of the Terrorism Act, and whether that legislation should be adjusted. Already, we are planning to limit the schedule 7 powers. We consulted last year on a wide set of improvements – such as reducing the maximum period of detention to six hours and allowing anyone detained for more than 60 minutes access to a lawyer. This autumn we will be taking a bill through parliament to implement these changes. In my view, if Anderson provides a clearly justified recommendation to restrict these powers even further, we should seek to do so in this bill.

There is a wider question, however, about this expanding world of data and information sharing. The power of information technology hasn't just transformed our daily lives, it has shifted the very boundaries of this ancient debate about liberty and security. These new technologies have extraordinary liberating potential but also pose new challenges and threats.

Criminals and terrorists now have access to a dizzying array of information, with devastating implications, while the security authorities have new tools with which to track them down. Data-mining techniques have the capacity to make government much more efficient but pose a real risk to personal privacy if taken too far. Social media can create new communities that would never have been possible before, but can also be the source of tragedy, as we have seen in a series of recent young suicides.

So a balance must be struck between a libertarian "anything goes" approach, which sees new technology as a way to escape from the reach of the law, and an authoritarian view that sees technology as a new opportunity to intrude into our lives. Technology will continue to evolve and governments worldwide will try to evolve with it. As long as Liberal Democrats are in government, I will ensure that our individual rights are not cast aside in the name of collective security.

• This article was amended on 23 August 2013 after a request from the deputy prime minister's office based on legal reasons. The footnote was amended on 25 August 2013 to give greater clarity.