Sites such as Facebook have been used to abuse people under the mask of anonymity
Websites will soon to be forced to identify people who have posted defamatory messages online.
New government proposals say victims have a right to know who is behind malicious messages without the need for costly legal battles.
The powers will be balanced by measures to prevent false claims in order to get material removed.
Last week, a British woman won a court order forcing Facebook to identify users who had harassed her.
Nicola Brookes had been falsely branded a paedophile and drug dealer by users - known as trolls - on Facebook.
Facebook, which did not contest the order, will now reveal the IP addresses of people who had abused her so she can prosecute them.
The new powers, to be added to the Defamation Bill, will make this process far less time-consuming and costly, the government said.
Complying with requests would afford the website greater protection from being sued in the event of a defamation claim. End to 'scurrilous rumour'
Currently, in legal terms, every website "hit" - visit - on a defamatory article can be counted as a separate offence.
This means many websites remove articles as soon as a defamation claim is made - either rightly or wrongly.
"Website operators are in principle liable as publishers for everything that appears on their sites, even though the content is often determined by users," said Justice Secretary Ken Clarke.
"But most operators are not in a position to know whether the material posted is defamatory or not and very often - faced with a complaint - they will immediately remove material.
Nicola Brookes said the abuse started after she posted a message about an X Factor star
"Our proposed approach will mean that website operators have a defence against libel as long as they identify the authors of allegedly defamatory material when requested to do so by a complainant."
Mr Clarke said the measures would mean an end to "scurrilous rumour and allegation" being posted online without fear of adequate punishment.
"The government wants a libel regime for the internet that makes it possible for people to protect their reputations effectively but also ensures that information online can't be easily censored by casual threats of litigation against website operators.
"It will be very important to ensure that these measures do not inadvertently expose genuine whistleblowers, and we are committed to getting the detail right to minimise this risk."