The price of source protection — a key tenet of a free, open press — is now approximately £43,000.

That is the cost Ian Paisley Junior will have to shoulder after being fined in Belfast High Court on 30 June for failing to disclose the identity of a source.

The source in question was a prison officer who Paisley Junior alleges told him that files relating to the 1997 murder of loyalist leader Billy Wright in the Maze prison had been destroyed.

At present, a public investigation, the Billy Wright Inquiry, is seeking all documentation and source material that may be related to the controversial killing inside a supposed top security prison.

From the outset Paisley Junior told the inquiry that he could not betray the source of his information and would rather go to prison than hand over the officer’s name.

The son of the Rev Ian Paisley lost his case on Tuesday and as a result was fined £5,000. The extra £38,000 is the legal costs he must pay for both the Crown’s and his own defence.

Although it has received less publicity than the case of Sunday Tribune journalist Suzanne Breen a fortnight ago, the Paisley Junior case is important for all of those who think the flow of information from anonymous sources is important in a free society. Breen won her battle to not hand over material related to interviews she conducted with the Real IRA on the grounds that her life could have been put in danger. Paisley Junior, while not under any physical threat, saw it as a matter of honour that he would keep his word and protect the identity of someone in the prison service whose exposure could have had serious consequences for his or her career.

The controversy also raises an important point about the role of public inquiries and the danger of them turning into inquisitors. Several journalists have come under pressure from inquiries such as the Bloody Sunday tribunal to reveal sources that preferred to remain anonymous. The argument from these reporters is essentially the same one as Paisley Junior mounted regarding the Bill Wright Inquiry — that to reveal the identities of sources is a betrayal of them and the slippery slope towards scaring off whistleblowers coming forward with information the public has a right to know.