The statistical inevitability of ISP porn filters blocking the wrong stuff

Even if it's an honest mistake, blocking useful sexual health and LGBT resources constitutes an inevitable encroach upon online civil liberties.

Consumers have had to put up with the government’s stupid, naive, and/or malicious decision to mandate the censorship of the internet in the UK that ISPs block certain “harmful” content for their customers’ own good for almost a month. The results are starting to roll in, and - unsurprisingly - they’re needlessly frustrating.

Over the course of Sunday evening and Monday morning this week, a crucial browser plugin called jQuery was listed by Sky’s filter as malicious, and the code.jquery.com site was blocked. jQuery’s a Javascript library that makes the language behind modern websites - HTML5 - work properly. Block jQuery, and a lot of the web stops working as smoothly as it should. Sky eventually fixed the problem, but the cause of the error is still unknown.

This follows on from the problems experienced by ISPs in December, when it became clear that the filters included sites offering sexual health advice, or advice on how to deal with abusive partners, as content that needed to be blocked.

As Martin Robbins laid out in the NS in December, there’s a massive gap between the PR-spin “porn filter” idea and the reality of an “objectionable content” filter. The former seeks to block something that doesn’t have a universal definition, while the latter does block sites of a set definition - set, that is, arbitrarily. It’s dangerous to enable censorship - by default! - of stuff that could save lives, just as it’s irresponsible to conflate kids accessing porn (which, by the way, has never been shown to cause long-term damage to children) and the very real problem of child pornography (or child abuse media, as it should really be referred to).

The most frustrating aspect of this problem might well be that it only takes a bit of back-of-the-envelope statistics to show how useless a concept porn filters as a tool, regardless of whether the sites are picked by algorithms or by humans. This is an argument Cory Doctorow has been making with characteristic intelligence and wisdom for years:

There simply aren't enough people of sound judgment in all the world to examine all the web pages that have been created and continue to be created around the clock, and determine whether they are good pages or bad pages. Even if you could marshal such a vast army of censors, they would have to attain an inhuman degree of precision and accuracy, or would be responsible for a system of censorship on a scale never before seen in the world, because they would be sitting in judgment on a medium whose scale was beyond any in human history.

Think, for a moment, of what it means to have a 99 percent accuracy rate when it comes to judging a medium that carries billions of publications.

Consider a hypothetical internet of a mere 20bn documents that is comprised one half "adult" content, and one half "child-safe" content. A 1 percent misclassification rate applied to 20bn documents means 200m documents will be misclassified. That's 100m legitimate documents that would be blocked by the government because of human error, and 100m adult documents that the filter does not touch and that any schoolkid can find.

In practice, the misclassification rate is much, much worse.

How much worse? Try a misclassification rate of more than 75 percent, according to the Electronic Frontier Foundation.

Or, as this tweet succinctly expresses:

In December, as Talk Talk discovered that its HomeSafe filter was blocking the site of LGBT organisation London Friend, its spokesman’s response, delivered on Newsnight, was telling: “Sadly there is no silver bullet when it comes to internet safety and we have always been clear that no solution can ever be 100 percent. We continue to develop HomeSafe and welcome feedback to help us continually improve the service.” ISPs are just as aware of how impossible a challenge it will be to develop a filter that’s a 100 percent safe.

The nuts and bolts work of combating child abuse is the work of a government agency that the coalition has limited by cutting its budget; it's instead hard not to sympathise with the argument (or is it conspiracy theory?) that the filters have been introduced as a kind of backdoor Section 28, designed to appease the puritanical dinosaur wing of the Tory party. And in the meantime, Chrome users with control over their computers can install the Go Away Cameron plugin, which will route around the filters using a proxy.

Sky's content filter in action.

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

Photo: Getty Images/Christopher Furlong
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A dozen defeated parliamentary candidates back Caroline Flint for deputy

Supporters of all the leadership candidates have rallied around Caroline Flint's bid to be deputy leader.

Twelve former parliamentary candidates have backed Caroline Flint's bid to become deputy leader in an open letter to the New Statesman. Dubbing the Don Valley MP a "fantastic campaigner", they explain that why despite backing different candidates for the leadership, they "are united in supporting Caroline Flint to be Labour's next deputy leader", who they describe as a "brilliant communicator and creative policy maker". 

Flint welcomed the endorsement, saying: "our candidates know better than most what it takes to win the sort of seats Labour must gain in order to win a general election, so I'm delighted to have their support.". She urged Labour to rebuild "not by lookin to the past, but by learning from the past", saying that "we must rediscover Labour's voice, especially in communities wher we do not have a Labour MP:".

The Flint campaign will hope that the endorsement provides a boost as the campaign enters its final days.

The full letter is below:

There is no route to Downing Street that does not run through the seats we fought for Labour at the General Election.

"We need a new leadership team that can win back Labour's lost voters.

Although we are backing different candidates to be Leader, we are united in supporting Caroline Flint to be Labour's next deputy leader.

Not only is Caroline a fantastic campaigner, who toured the country supporting Labour's candidates, she's also a brilliant communicator and creative policy maker, which is exactly what we need in our next deputy leader.

If Labour is to win the next election, it is vital that we pick a leadership team that doesn't just appeal to Labour Party members, but is capable of winning the General Election. Caroline Flint is our best hope of beating the Tories.

We urge Labour Party members and supporters to unite behind Caroline Flint and begin the process of rebuilding to win in 2020.

Jessica Asato (Norwich North), Will Straw (Rossendale and Darween), Nick Bent (Warrington South), Mike Le Surf (South Basildon and East Thurrock), Tris Osborne (Chatham and Aylesford), Victoria Groulef (Reading West), Jamie Hanley (Pudsey), Kevin McKeever (Northampton South), Joy Squires (Worcester), Paul Clark (Gillingham and Rainham), Patrick Hall (Bedford) and Mary Wimbury (Aberconwy)

Stephen Bush is editor of the Staggers, the New Statesman’s political blog.