Ministers and judges will never succeed in taming the "immensely powerful" internet, the chair of the Commons' culture, media and sport committee has told Politics.co.uk.
John Whittingdale said the government could only go so far in preventing the "dark side" of the online world from defaming individuals, infringing on their privacy and spreading pornography because of the global nature of the internet.
"However much you try and legislate to cover UK-based publishers, there will always be some beyond the reach of the law which it is almost impossible to legislate over," he explained.
His warning came as the Speaker of the Commons' wife Sally Bercow faces legal proceedings brought against her by Lord McAlpine, whose name was falsely associated with paedophilia accusations on social media sites like Twitter.
The test case is the first of its kind and will establish case law, demonstrating the extent to which the courts are willing to punish people who are breaking injunctions online, Whittingdale said.
Such "groundbreaking" developments will not bring the internet fully under control, however.
"This is one of the reasons why Lord Justice Leveson devoted a page or not much more of his massive four-volume report to the internet," Whittingdale added.
"Not because the internet is not important, it plenty is, but because it is very unclear as to actually how much you can do to control it. It is immensely powerful. The world has changed as a result of this power."
Page 736 of the Leveson report observed that the internet "does not claim to operate by any particularly ethical standards, still less high ones. Some have called it a 'wild west' but I would prefer to use the term 'ethical vacuum'".
Despite the absence of any explicit assessment of the way in which online publications go about their business, parliament tried to impose statutory regulation on websites following cross-party talks.
But after consultations with websites the Department for Culture, Media and Sport chose to exempt websites which employ ten or less people.
"There is a dark side where it can be abused and government has to look at ways to try and prevent that abuse," Whittingdale said, "but you should never lose sight of the fact it has brought huge advantages. It has been in many countries an immense force for progress."