Scotland’s main legal reform body has proposed new defamation laws campaigners believe will help stop “vanity cases” designed to silence critics.

The Scottish Law Commission has drafted a bill as part of its ongoing consultation on bringing archaic laws in to the internet age

Its efforts came after campaigners, including this newspaper, warned unreformed defamation laws were having a chilling effect in Scotland on investigative journalism and freedom of speech.

In their bill Law Commissioners, who advise parliament on reforms, have come up with Scots Law reforms designed to replicate and improve on changes made to English libel rules in 2013.

Commissioners have suggested a statutory public interest defence and, crucially, say campaigners, a new rule under which those suing for defamation have to prove ‘serious harm’.

Campaigners, such as Freedom of Expression group Scottish PEN, argue the rich and powerful - or those with access to mass fundraising - can currently use defamation laws to silence critics on relatively unsubstantial grounds.

A spokesman for Scottish PEN said there was “much to be optimistic about” in the proposed bill.

He said: “ Steps to establish both a serious harm threshold and a statutory public interest defence will bring about a significant barrier to vanity cases brought solely to silence others and stifle criticism and debate. “

Critics of the current law have warned that those who go online to express views are vulnerable to disproportionate legal action, as are those who host those views. such as the social media providers.

The Scottish PEN spokesman said: “Individuals who communicate online should welcome the move to establish protections for secondary publishers and a single publication rule that will ensure liability does not continue ad infinitum when an out-dated link is shared or retweeted.”

He added: “This is a significant step in the right direction but we cannot be complacent. Defamation laws affect everyone; facebook group moderators, bloggers, social media users, journalists, politicians, activists, writers and civil society more broadly.

“So we need everyone to speak up and take part in the consultation to ensure the Scottish Law Commission prioritises reform that protects free expression for all.”

The Law Commissioners have suggested writing in to statute a legal convention, untested in Scotland, that public bodies cannot sue for libel. However, they have declined to support proposals that commercial bodies should also be prevented from doing so. Campaigners had hoped only real people, not corporations, could sue.

The Law Commission has published its bill on its website and asked for comment by the end of the month. Previously some lawyers have suggested that there is not enough case law to show a need for reform. Defamation actions are rare, threats of action are not.

The reforms proposed in the new bill are in broad line with changes sought by The Herald’s long-standing Freedom of Speech campaign.

The Law Commission will publish a draft report on reform by the end of the year. Holyrood will have the final say.