In practice such targeting means working out what a web user is interested in. And therein lies the problem: gathering information and building up profiles, if not done in a sensitive and transparent manner, can look an awful lot like snooping. [...]
Several American ISPs have quietly switched on NebuAd's system, inserted a brief reference to it in their terms and conditions, and hoped that nobody would mind. Britain's biggest ISP, BT, secretly tested Phorm's technology last year, perplexing some clued-up users who wondered why their traffic was being intercepted. Activists and politicians have questioned whether all this violates privacy or wiretapping laws. Britain's Information Commissioner has warned that such systems should be “opt in”, and in America two congressmen have questioned the “opt out” approach of the NebuAd system that is being used by Charter, the country's fourth-largest ISP.
Attempts to sneak in behavioural-targeting systems through the back door could give a promising idea a bad name. Done properly, behavioural targeting promises to make advertising more relevant for consumers, to increase conversion rates for advertisers and to make online publishers' advertising slots more valuable (since even slots on obscure web pages can have relevant ads placed in them). [...]
But as behavioural-targeting systems become more sophisticated and invasive, it is vital that the companies behind them are open with users about what is going on, and give them control over their personal information. “It's mine—you can't have it,” says Sir Tim Berners-Lee, the inventor of the web, of such information. “If you want to use it for something, then you have to negotiate with me.”
Behavioural-targeting systems that intercept web traffic should be “opt in” rather than “opt out”. Customers may, for instance, be happy to opt in if they are offered a discount on their broadband bills: after all, most web users seem to be willing to reveal some personal information provided they get something in return, such as free web-mail or the use of a search engine. But unless they play fair, the proponents of behavioural targeting risk ruining a promising new idea.