Well, this is huge, so I'd like to draw your attention to what's happening right now. This is a very alarming case, and it concerns every ad blocker user.
Brief introduction into ad blocking
To understand better what's happened, you should first learn a bit more about ad blocking. Every ad blocker work is based on using so-called filters lists, which are maintained (mostly) by volunteers. That said, whichever ad blocker you use, credits for actual ad blocking belong to the filter lists maintainers. The most popular filters list is called EasyList and this is what this story is about.
Got it, so what happened?
Yesterday a strange commit landed in the EasyList repo. The "functionalclam.com" domain was removed with a comment "Removed due to DMCA takedown request".
An ad server was unblocked by all ad blockers due to a DMCA request. Let that sink in for a moment...
A small research was conducted by the community in the comments section of that commit. It appears that the story began 23 days ago with a comment by a freshly registered Github account to the commit that added "functionalclam.com" to EasyList. @dmcahelper threatened with "the file or repository disruption," but his threats were not taken seriously that time.
The domain in question hosts an image describing its work as "used by digital publishers to control access to copyrighted content in accordance with the DMCA and understand how visitors are accessing their copyrighted content".
However, further research showed that this domain hosts the code of an anti-adblocking startup Admiral, so we can assume that it is the company we should blame for this. Where did they get this glorious idea? The wording of the original comment from 23 days ago reminds me awfully of this post claiming that DMCA can be applied to ad blockers.
Why should I care?
This might set a very important precedent of an advertising company exploiting DMCA to force people to see their ads, and can lead to ridiculous consequences if left unnoticed.
EasyList is a community project and may not be able to protect themselves from such an attack. I am calling on other ad blockers developers, you people and everybody else concerned about people's rights (EFF, please) to stand up to this threat and protect ad blocking.
UPD (11 Aug, 8:09GMT): EFF representative offered their help to EasyList maintainers.
UPD (11 Aug, 11:34GMT): Filters maintainers commented on the situation:
We received a DMCA request from Github, as the server in question may've been used as Anti-Adblock Circumvention/Warning on some websites. To keep transparency with the Easylist community,
the commit showed this filter was removed due to DMCA.
We had no option but to remove the filter without putting the Easylist repo in jeopardy. If it is a Circumvention/Adblock-Warning adhost, it should be removed from Easylist even without the need for a DMCA request.
In regards to Adblock-Warning/Anti-adblock, the amount of filters being added recently to Easylist has been greatly limited due to issues like this. As list authors we have to be careful in what we add.
We'll certainly look at our legal options and it will be contested if we get DMCA requests for any legit adservers or websites that use DMCA as a way to limit Easylist's ability to block ads.
UPD (11 Aug, 13:13GMT): Comment from Admiral
UPD (11 Aug, 17:05GMT): Original DMCA notice is now available
UPD (11 Aug, 21:13GMT): Github representative commented on the situation