The authorities will be given access to the data only as part of ongoing criminal investigations. The ISPs have been told to log information such as connection times, e-mails sent and received and the recipients of these e-mails. However, they will need further authorisation to access the actual content of an e-mail.

The scope of the new powers remains quite limited, and is restricted to certain types of crime such as drug trafficking and paedophilia. A judge will have to issue a search warrant for the data to be scrutinised, and in some cases, suspects will have to be informed of the investigation.

Not surprisingly, this has greatly increased the compliance burden for Swiss ISPs, which have had to install sophisticated new equipment, often at great expense. Though the ISPs have had a year to come into compliance with the changes, some say they are still not ready to implement the technology.

To put the task into context, one ISP, Infomaniak, says it will have to monitor 300,000 emails a day if asked to log the activity of just one customer. Head of the Geneva based ISP, Fabian Lucchi, even suggested to the Swissinfo news service that the new law will be unworkable due to the sheer amount of storage space required for the data. "Storing everything for six months just defies the imagination," he observed.

The sheer cost of implementing the new equipment has caused some smaller ISPs to warn that they will have to pass on the cost to the user.

Critics argue the new law is full of loopholes that will enable criminals to easily bypass the legislation. For instance, company and university servers are not included in the scheme, nor are e-mails sent from internet cafes. Criminals using 'hotmail' accounts on international servers will also escape unseen.

Then there is the cost of actually mounting e-mail surveillance to be considered. Federal law stipulates that ISPs can bill the authorities up to SFr 750 ($550) just for accessing their data. A long-running and complicated case could soon see the costs mounting.