Journalists have a moral duty to protect the confidentiality of their sources, even at the cost of going to prison themselves.
As a result of one young journalist, Bill Goodwin, being prepared to take that risk, the European Court of Human Rights ruled in his case against the UK that all journalists had a presumptive right to resist legal demands to identify those who privately pass on information: "Protection of journalistic sources is one of the basic conditions for press freedom ... without such protection, sources may be deterred from assisting the press in informing the public on matters of public interest.
"As a result the vital public watchdog role of the press may be undermined and the ability of the press to provide accurate and reliable information may be adversely affected."
The cultivation of sources is thus essential, for journalists and for the public they serve. It is a basic tool of their trade, the means by which newsworthy information is extracted from powerful corporations and government departments which want to keep wrongdoing secret or give it a particular 'spin'.
Without the ability of journalists to promise anonymity to sources who fear reprisals, and to keep that solemn promise, there would be a lot less news and what there is would be less reliable.