A controversial plan to store information about personal internet and telephone usage in Australia has been criticised by the world wide web's inventor, Sir Tim Berners-Lee.
Internet service providers and telecommunications companies would be asked to store data that passes through their networks for up to two years, under plans being considered by the federal government.
Law enforcement agencies want the data retained to help fight crime.
Speaking in Sydney on Tuesday, Sir Tim said any such law would do little to catch serious criminals because they would find ways around it, including using encrypted and secure networks.
He believes the stored databases "won't contain information for stopping serious criminals, only the people who've taken out too many library books".
The British academic is also concerned about how very personal data could be used.
"These logs have got data on what websites you've gone to.
"You could find out when someone's gone to a health (web)site ... and in the URLs you will see exactly what sort of cancer they are worried about.
"You'll produce a world where a teenager who really needs to visit an online forum to get some professional advice ... realises that if they click they'll be branded for the next two years, having gone to that site."
Attorney-General Nicola Roxon told a security conference in September there may be a case for the data retention law.
"Many investigations require law enforcement to build a picture of a criminal activity over a period of time; without data retention, this capability will be lost," she said.
A federal parliamentary committee considered the laws last year.
Its report concluded that data retention may `sound like a sensible solution' for law enforcement agencies who want access to data for crime fighting purposes.
But it noted concerns about the security of the data - and the cost of storing it - which must be addressed and resolved.