How common are 'time-wasting' appeals against government?

The prime minister says he wants to help major infrastructure projects to flourish

Prime Minister David Cameron has expressed his determination to crack down on "time-wasting" caused by the "massive growth industry" in legal challenges to government policy.

But just how real is this problem?

The figures for judicial review quoted by the prime minister are overall figures.

In other words, they cover all judicial reviews and not just those in respect of building and planning developments, or judicial reviews related to business growth.

Individuals and organisations can seek a judicial review if they think a decision by a public body has been made unlawfully.

The review, carried out by a judge, looks only at the way the decision was reached - rather than whether it was correct or not.

There were 11,200 applications for permission for judicial review last year.

And that does represent a trebling of the overall figures in around a decade.

But what the prime minister did not say is that the majority of those applications are in one area - immigration and asylum.

That is where the real growth has been.

They represented half of all cases in 2001. That rose to three quarters of all cases in 2011.

What does that seem to tell us?

Simply that outside immigration and asylum, there has been a modest increase, and not a huge explosion of cases.

The figures are categorised as immigration, crime and "other".

It is that "other" category - and the commercial planning and building judicial reviews within it - that the prime minister seemed to be focusing on.

However, "other" includes all sorts of cases, not just judicial reviews that relate to commercial planning and building.

The Ministry of Justice told the BBC that it does not have any figures for the number of reviews related to building and planning.

But lawyers who practise in this area say that it may be a very small number of cases.

One said it could be a "vanishingly small" number.

It was his view that there really are not a lot of judicial reviews holding up commercial building projects.

Where everyone acknowledges that there is a real problem is that the courts are clogged up, and once the initial permission is granted, it can take years for a "JR" to be heard.

So, there has been a rapid growth in the numbers of cases waiting to be tried.

Some lawyers argue that is more of a resourcing problem for the courts system and that if more judges were assigned to judicial review cases, the problem could be eased.