Scotland's most celebrated writers have warned of a threat to their freedom of speech.

James Kelman, Ian Rankin, Val McDermid, Chris Brookmyre and Neal Ascherson are among more than 100 authors demanding reform of the country's antiquated defamation laws.

In a joint letter organised by freedom of speech organisation Scottish Pen, the writers warn that they - along with campaigners, scientists and journalists - are facing the "chilling" effect of libel action threats.

The Herald: Herald Freedom of Speech CampaignHerald Freedom of Speech Campaign

Their concern, backed by The Herald's "Freedom of Speech" campaign, which launches today, is that libel reform south of the border makes Scotland a soft target for those who wish to silence their critics across the UK.

The writers said: "In England and Wales, citizens now have more freedom to debate the issues that matter to ordinary people.

"Unfortunately, MSPs have never been given the chance to address this area of law.

"Citizen campaigners and investigative journalists in Scotland can still face defamation threats from wealthy individuals and companies who do not care to be criticised, and there is now a risk that libel tourists will start bringing cases to Edinburgh."

The Herald: James Kelman is one of the writers backing defamation reformJames Kelman is one of the writers backing defamation reform

Scotland has not reformed its law of defamation since long before the world wide web was a reality.

That, warn the writers, leaves Twitter, Facebook and Tripadvisor and their millions of users at risk of being sued.

The Herald:

The writers, in a letter published in today's Herald, said "A modern and open nation like Scotland deserves a defamation law that is fit for purpose in the 21st century: one that acknowledges the existence of the internet, and enables journalists and authors to conduct a robust debate on matters of public interest."

The Scottish Government initially rejected moves to reform libel laws along the lines of England and Wales.

Crucially, these means that Scotland does not have an English-style "serious harm" test for legal actions for defamation.

The Scottish Law Commission, however, is now looking at potential reforms to libel amid growing awareness among lawmakers and lawyers of a serious weakness in legislation.

The Scottish Government, which has said its position on defamation is "under review", does not have to adopt Commission recommendations. Any changes would have to be approved by parliament.

But, for the time-being, those who feel defamed can sue even when there their reputation has only suffered slightly.

The Herald:

Scottish Pen stressed this could pave the way for libel tourism, when those who cannot take action in an English court do so in Scotland instead.

Already at least one litigant is understood to have travelled from London to Edinburgh in an attempt to sue over what he or she regarded as an offending article north of the border.

Scottish Pen said: "The current disparity between Scottish and English law continues to cause confusion on both side of the border, forcing publishers, journalists and writers throughout the UK to be more risk averse to avoid being sued in Scotland.

"We currently have a two-tiered system that opens up writers, journalists and publishers throughout the UK to undue threats that severely limit what can be published, as they are open to the threat of defamation in Scotland and Northern Ireland.

"This is a chance for Scotland to take the lead to call for fair and transparent guidelines that maintain robust public interest protections and fully take on board online and social media publications that can encourage similar actions to take place in Northern Ireland.

"Only then can we be sure that the UK remains a safe and free place for journalists, writers and publishers to operate."

The organisation stressed that the chilling effect of out-of-date libel laws was probably having the biggest effect on new or independent online media outlets which emerged during or after the independence referendum.

It said: "This is a dire threat to both media plurality and the diverse media landscape in Scotland that continues to grow amid continued challenges across both the industry and the country."

Concerns aren't new. English campaigners first raised their fears about Scotland last year.

Signatories to the Scottish Pen letter also include Sara Sheridan, Mairi Hedderwick, Alan Bissett and Aonghas MacNeacail.

The full letter and all its signatories can be read here.

The Herald view in full.