A constitutional outrage and a step towards a Stasi state (or a fascist one if you prefer)? Or just a minor Westminster storm in a chattering classes teacup?

Damian Green is hardly my favourite politician and it's tempting to sit back and laugh at him being subjected to such indignities.

But that is not the point.

When Robert Mugabe wanted to put down the increasingly popular opposition party in Zimbabwe, the Movement for Democratic Change, his security forces raided their offices and arrested its leader, Morgan Tsvangirai.

So what is the world to think now about the actions of the Metropolitan Police?

Of course we still live in a democracy and one dawn raid doesn't alter that.

But it doesn't bode well either.

Let's recap.

Damian Green is a leading opposition MP who received and published leaked documents from the Home Office.

None of them compromise national security though some are an embarrassment to the government.

Some included information that should have been revealed.

This is what opposition MPs (and indeed government backbenchers) have done for as long as we can remember.

The leakers may sometimes be breaking the law. The MPs are doing a part of their job - to hold the government to account.

Some people say politicians are "all the same" and others ask "why can't you all work together for the common good?"

But we don't.

We have governments and oppositions and we have MPs (and peers) part of whose job is to look critically at what the government is doing and to bring out into the open the things that are going wrong.

It comes down to the famous aphorism by Lord Acton - "All power tends to corrupt; absolute power corrupts absolutely."

If everyone worked together "on the same side" there would indeed by absolute power reigning in the land.

Politics may be messy and argumentative and there may often be more heat than light.

But our liberties depend on it.

We are still a democracy and the proof is that the top people who may or may not have ordered or condoned the disgraceful action against Mr Green are now, we can hope, being called to account.