Qatar residents woke up Sunday morning to find that the popular blogging site Tumblr had been blocked by Qtel’s morality sensors. 

Problems accessing Tumblr were also reported in Yemen, Kuwait and the UAE.

The reaction was fast and furious, and Qtel quickly apologized for what appeared to be a big mistake. By Sunday afternoon, Tumblr was back.

So what happened? And more importantly, can it happen again?

Helmi Noman, a research associate at Harvard’s Berkman Center for Internet and Society who works on the Opennet Initiative, gets to the bottom of things.

Noman says the decision to block Tumblr was made in Canada by a company that that provides filtering technology to internet service providers in Qatar, the UAE, Yemen and Kuwait.

Netsweeper categorizes Tumblr under “Journal and Blogs” but also under “Pornography,” which rendered all blogs hosted by the service inaccessible for the four countries that use Netsweeper to do its filtering.

The incident is worrying for two reasons, Noman says:

• Netsweeper provides the ISPs with both the technology used to censor, but also makes on their behalf decisions as to what is appropriate/inappropriate to access by citizens using the relevant ISPs.
• Artificial intelligence is not always intelligent. Netsweeper, like other commercial Internet filters, relies on artificial intelligence to analyze content of websites and to make decisions as to how each URL should be categorized. This mechanism is evidently fragile and, as a result, the flow of online information gets disrupted.

So there you have it. Tumblr was blocked in several Arab countries because a Canadian company has classified it as porn.

Read the full story here.

Noman and colleague Jillian C. York further explore the topic of censorship in the Middle East in a report titled, “West Censoring East: The Use of Western Technologies by Middle East Censors.”