Both the Tribunal and the Commissioner argued that this is an exceptional case where it would be in the public interest for cabinet minutes to be published, but Jack Straw argued that publication would damage cabinet government.

Straw stressed that this is the first time in the four years since the FOI law came into effect that the ministerial veto has been used, and he maintained that its use would be rare.

But there are concerns among FOI campaigners that this sets a precedent and the veto may become more common (as highlighted on this blog in January). In this context it is interesting to note that the Conservatives backed Straw's decision to use the veto.

In other countries with FOI laws, the ministerial veto has been used with some regularity once first deployed. As noted by the Constitution Unit [pdf link] it has been used most heavily in Australia - 55 vetoes were issued in Australia between 1983 and 1987, and 14 by the Howard government between 1996 and 2007, while in New Zealand the veto was used 14 times in the first four years.

This is a long-running legal saga which has often been written about on this blog (for example, here and here) and has not yet ended.

Some of the headlines (like this and this) on this decision are misleading, so it is important to be clear about the implications of the latest ruling.

Yesterday's Law Lords decision was not about the merits of whether the report should be published. It was about the procedural legal matter of whether the Information Tribunal (which supported publication) has the jurisdiction to rule on such cases, where the Information Commissioner has previously decided that the request was outside the realm of FOI in the first place because it involved information held by the BBC for the purposes of journalism. Material of this kind lies outside the Freedom of Information Act, and the BBC has argued that the Balen Report falls into this category.

The Lords determined (against the views of the Court of Appeal and the High Court) that the Tribunal does have the right to consider such cases, so its ruling in favour of publication is valid. The substantive arguments on whether the report should be made public can now move on to the High Court, assuming the BBC maintains its stance.

The decision refers to meetings that discussed the the attorney-general's legal advice about the Iraq war. But the particular significance from an FOI point of view is in the precedents that this case may create.

Some are asking whether it is a green light for the release of other cabinet minutes. The Tribunal says not necessarily - under the FOI Act, every case has to be assessed on its own merits. But it may pave the way for a potentially more important precedent.

The government has argued that releasing such minutes would impede proper recording of free and frank discussion within cabinet. It is likely to resist the ruling, either by appealing to the High Court or by using the ministerial right to veto a Tribunal decision for the first time.

To use the veto will cause a big fuss - but the government could see this as a strong case for doing so, then making it easier to do so again on future occasions once a precedent has been established. That is why some FOI campaigners have been feeling rather uneasy about this case, fearing that this Tribunal decision in favour of greater openness could, ironically, turn out to be a setback for their cause.

Yesterday's government climbdown over the proposal to change the law to block the full release of MPs' expenses under FOI means that the experience of FOI in the UK, in at least one way, contrasts with that in some other countries.

In many places, the introduction of FOI has been followed by a backlash from those in authority which has led to restrictions on access to information. In Ireland, for example, a few years after the introduction of FOI laws, the government introduced up-front fees for FOI requests which has greatly reduced their number.

However, in the UK there have been three attempts to cut back on the access provided by the law since FOI was introduced in 2005, and none of them has succeeded.

The first was David Maclean's bill, which would have exempted Parliament from FOI. It failed when no-one would sponsor it in the House of Lords. The second was the government's plan to make it easier to reject FOI requests as too costly. Gordon Brown dropped this proposal after he took over from Tony Blair as prime minister, proclaiming his support for open government. And the third was this latest attempt.

FOI was once regarded as an issue of concern to the "chattering classes", but it now seems, in the UK at least, to have acquired more populist overtones. And President Obama too is pledging a new "era of openness".