I was informally interviewed in recent weeks about the story, which centred on a report by Senior Counsel George Birmingham into the Dean Lyons affair.

Dean Lyons was allowed to wrongly confess to the murders of two women in Grangegorman hospital in March 1997 and was subsequently charged. I wrote a series of articles based on Birmingham's preliminary report which had not yet been published but was completed and gathering dust in the department. This resulted in the department's Secretary General Sean Aylward making a formal complaint to the garda commissioner. A sevenmonth investigation into the story led to my arrest last week as well as that of a garda detective.

I had a feeling that there was a possibility that I would be detained and went to the station accompanied by my solicitor. I was arrested on the pavement outside Harcourt Terrace under Section 4 of the Criminal Justice Act. I was brought into the station and processed. This involved gardai taking my personal details and informing me of my rights while in custody. I was then photographed and fingerprinted and consulted with my solicitor before being interviewed.

I was interviewed on a number of occasions during my eight hours in custody. These interviews were recorded on film which is a standard procedure these days. For legal reasons I cannot go into any detail about what was said, but as a journalist all sources are sacrosanct and I, like all my colleagues, would be prepared to go to jail to protect any and every source if the need arose. It was not a nice experience being arrested.

However, my time in garda custody was made far easier by the conduct of the three detectives who interviewed me. They were courteous, respectful and highly professional and went out of their way to ensure that I had everything I needed. I was not treated any differently to anybody else just because I was a journalist. I saw a number of prisoners being processed throughout the day and they were all dealt with to the same high standards by the gardai at Harcourt Terrace.

I have absolutely no issue or gripes with the gardai for arresting me. They were acting on foot of a complaint from the Department of Justice and had to investigate that complaint seriously. I don't necessarily think that a team of serious crime detectives wanted to spend seven months investigating me when there are criminals walking the streets but they had no choice.

I do have a number of concerns with the Department of Justice though. Its secretary general made a complaint after my articles appeared on 10 and 11 August 2006. An Tanaiste Michael McDowell went on the record in the Dail saying that the Evening Herald was informed that it was in breach of the Commissions of Investigation Act before the story was published. He is wrong. I rang the duty press officer in the department on the evening of 9 August to inform him that I was running the story the following day. I left a message for him to contact me.

He never did.

The following morning I again attempted to contact him before 8am.

There was no answer. He finally returned the call at 8.30am and refused to comment on the story.

The first edition of the newspaper went to print at 9.15am and I was eating my breakfast at 10.40am when the press officer rang my mobile phone. He quoted the relevant legislation of which the newspaper was in breach. I had never heard of it.

It came into law in 2004 and had never been used before. I arrived back at my desk to find an email from the press officer waiting for me. I then learned that the legislation provided for a 300,000 fine or five years imprisonment for publishing extracts of a report before it was officially released.

That email was sent at 10.45am, 90 minutes after the paper went to print.

I am not saying that either myself or the editor of the newspaper would not have run the story had we known of the penalties but the fact is, we weren't informed and given the option.

I became a journalist because I wanted to tell the truth and expose wrongdoing. Every scandal in this country over the last 15 years was exposed by brave journalists eager to highlight injustices. I am not professing to be a brave journalist but what happened to Dean Lyons was a gross injustice which came about by mismanagement by senior gardai.

They didn't listen to doubts that their junior colleagues had expressed and Birmingham said in his report that had these reservations being acted on Lyons would never have been charged.

I feel that my arrest last week is a very serious development aimed at curtailing the freedom of the press. I believe that Michael McDowell does not want gardai to talk to the media and think that the government and political parties in general would like newspapers to be little more than pamphlets outlining their objectives and achievements.

It is ironic that McDowell's department complains to gardai about leaks when it leaks stories to its favourite media partners on a daily basis. The tanaiste himself also has a chequered history when it comes to revealing confidential information.

McDowell spoke in the Dail about how he likes me as a person. I have been out socially with him on occasion and we get on very well. I have supported him as minister for justice and feel he has achieved a lot. I have to say though that his professed ignorance of my arrest is a bit rich. I have no doubt whatsoever that he was informed in advance that I was going to be taken into custody. In a democracy the arrest of a member of the fourth estate is obviously going to provoke an outcry and it is inconceivable that the Garda Commissioner didn't let him know in advance.

In the days after he became tanaiste and a month after the contentious article was published I met McDowell in an informal setting and jokingly asked him if I was going to be arrested over the Lyons controversy. He told me that I'd be okay and not to worry. It was very much an off-the-cuff remark but I felt after hearing it that things would be alright and I had nothing to be concerned about. He says he didn't know at this meeting that I would be arrested and I have to take him at his word.

The support that I have got over the last few days from across the media industry and the public in general has been unexpected. In an era where competitive pressures mean that rivalries exist between individual papers and journalists it is heartening to see the industry unite against draconian tactics designed to muzzle the free press. In the future I would like to think that I will continue to write about injustices without fear or favour, regardless of the consequences.

I really hope that this sorry episode will not result in gardai and other sources turning away from the media.

Discourse between gardai and journalists has taken place for decades and has generally worked well and has not been abused by either party. It would be a shame if an act of overzealousness by a government department would change this.

Regardless of the want of some of today's politicians, a free press will exist long after they retire. The truth will continue to be told.