Ad blockers are completely legal, but the detection of an ad blocker by using a script is technically illegal, it was argued today (18 April) at an Ad Week Europe session.

It was Alexander Hanff, a privacy consultant and campaigner for Think Privacy, who raised the issue during an industry panel at Advertising Week Europe earlier today (18 April), that included speakers from Ad Block Plus and The Guardian.

“Calling users criminal is not relevant to UK law," continued Hanff, who was referring to an earlier statement by Richard Eyre, chairman of IAB UK, who argued that ad blocker users could be deemed as “thieves”.

Hanff said he had received written confirmation from the DCMS that the use of ad-blockers was legal, but the Department did not comment on use of ad-blocker-blockers. Hanff said in the session that he had spoken to EU regulators who are of the view that they aren't legal, referencing the Guardian’s recent trialling of whitelisting content.

He went on to explain that the Guardian’s social media management software provided by Tribal Fusion enables tracking and data mining of users “without the consent of the user to allow that tracking of data” in order to feed back to advertisers. This lack of transparency with internet users about how and where their data is being used is a driving factor for the rise of technology such as AdBlock Plus.

Meanwhile, the developer behind AdBlock Plus “felt like he was killing the free internet” according to its ops and comms manager Ben Williams, who said his business has tried a lot of different solutions with whitelisting in its early form to counter this. He said users did not respond well to the ad-tech company’s experimentation with whitelisting and asked the company to remove this function.

“We felt Adblock Plus was set up in the wrong way,” Williams said. “That is why we tried to set up whitelisting.”

It’s why AdBlock Plus developed Acceptable Ads, as a compromise between user and publisher. He confirmed a small percentage of advertisers pay for this but assured “you can't pay to play”.

For a publisher, improving privacy and security is not very relevant in the ad blocking issue, since “this is not the main reason people install ad blockers”, with only 13-15 per cent of users choosing extra privacy protection on ad blocking software, Williams confirmed.

Instead, the focus is on advertising format, with Williams saying: “We felt we needed to attack one thing and we decided to choose format. If advertisers abide to that they can be whitelisted”.

AdBlock Plus is set to relinquish control of what is deemed an ‘acceptable ad’ and give that to an independent regulator by the end of the year.