Existing law says that companies not directly responsible for a message can escape liability for it but only if they take it down 'expeditiously' when informed of it. Liberal Democrat peer Lord Lester has proposed a Libel Bill which would set that period at 14 days, or shorter if an application to a court to shorten the period in a particular case is made.

"This means that ISPs, blogging platform providers and others who have an indirect role in publishing content now know how long they have to act on a complaint," said David Woods, a litigation expert at Pinsent Masons, the law firm behind OUT-LAW.COM. "The 14 day period is a surprisingly long one, considering how serious libel actions can be."

Though the Bill has been proposed by a Liberal Democrat, it has no guarantee of becoming part of the programme of the current Government.

The Conservative and Liberal Democrat parties both pledged to reform libel laws before this year's general election but a Ministry of Justice spokesman said that the coalition Government has not yet decided whether to back the Bill.

“We welcome the detailed consideration that Lord Lester has given to these important issues," said the spokesman. "His proposals cover a wide range of issues, and we want to give them careful consideration before reaching a view on the Government's position.”

The existing libel laws have been criticised by activists such as the Libel Reform Campaign as being unjust, costly and out of date. Even the last Labour Government said that it went too far in protecting reputations and posed a risk to free speech, particularly in the fields of academic research and science journalism.

Lord Lester's Bill addresses many of those concerns. It says that a writer or publisher would not have committed a libel if they publish responsibly in a matter of public interest. That protection is offered for statements of fact or expressions of opinion, two kinds of expression treated differently under current libel laws.

The Bill says that courts should take into account circumstances such as what a reporter knew; whether a publication complied with a code of conduct or offered an opportunity to comment; and how they verified their story before the publication of an article when considering whether or not to allow them the public interest defence.

The Bill also effectively reduces the length of time in which a libel action must be taken. Under current law the constant availability of an article online can extend libel's one year limitation period practically indefinitely. The Bill's 'single publication rule' says that the period within which action must be taken should run only from the article's first online publication, though it does not say how quickly after that action must be taken.

The Bill replaces the existing defence of 'fair comment' which has been established by case law and protects the expression of reasonably held opinions. The Bill puts this into the law directly and renames it 'honest opinion'.

The proposed new law sets a new standard which people and companies must meet if they are to claim they have been libelled. Companies should only be allowed to take cases when they can show that the libel will cause them "substantial financial loss". Individuals have to show that it would cause "substantial harm" to their reputation before the action can continue, it said.

The UK's libel laws have attracted many foreign cases because they are seen as being favourable to people trying to protect their reputations. The Bill attempts to solve this so-called 'libel tourism' by saying that an action can only be taken in the UK if its publication here caused substantial harm.