On almost any given day, Twitter receives a handful of requests to delete tweets that link to pirated versions of copyrighted content—and quickly complies by erasing the offending tweets from its site.

That fact itself is probably unsurprising to people familiar with the Digital Millennium Copyright Act (DMCA) takedown process, which gives sites like Twitter a "safe harbor" against lawsuits related to user behavior and uploads—so long as the sites don't knowingly tolerate pirated material or links to such material.

But Twitter has taken the unusual step of making DMCA takedown notices public, in partnership with Chilling Effects, a project of the Electronic Frontier Foundation and several universities. The site shows 4,410 cease and desist notices dating back to November 2010. While most of 2011 shows daily or near-daily activity, there is just one notice in January 2012, suggesting either that Twitter is suddenly receiving fewer DMCA takedown notices or that the database is not quite up to date. (If we find out from Twitter or Chilling Effects, we'll update the story.)

Scrolling through recent takedown notices, you'll see names like Magnolia Pictures, Simon and Schuster, Warner Music Group, Universal Music Group, among those of many other media companies. A typical takedown notice contains links to tweets that in turn link to websites where pirated versions of copyrighted material is distributed. Attempting to locate the actual tweet from the notice invariably leads to a Twitter.com error page saying "Sorry, that page doesn't exist!" Movies, music, footage of cricket matches and stolen photographs of an actress in states of undress have all inspired DMCA notices.

Twitter was already submitting data to Chilling Effects prior to this week, but this latest iteration makes it easier for users to locate Twitter-specific takedown notices. If you search the Chilling Effects site, you can also find many thousands of DMCA notices issued to Google, but Facebook has kept its own notices private.

Twitter's censorship process accompanied by greater transparency

Twitter's history of deleting tweets to gain safe harbor under the DMCA illustrates that it's not strictly an anything-goes platform, but Twitter says it at least wants to make the deletion process transparent. "One of our core values as a company is to defend and respect each user’s voice," Twitter said. "We try to keep content up wherever and whenever we can, and we will be transparent with users when we can't. The Tweets must continue to flow."

Twitter's expanded partnership with Chilling Effects was announced along with Twitter's new program to censor tweets on a country-by-country basis.

"As we continue to grow internationally, we will enter countries that have different ideas about the contours of freedom of expression," Twitter said yesterday. "Until now, the only way we could take account of those countries’ limits was to remove content globally. Starting today, we give ourselves the ability to reactively withhold content from users in a specific country—while keeping it available in the rest of the world."

Twitter's new policy has been criticized for allowing censorship, but EFF Legal Director Cindy Cohn tells us it is actually a positive step that will lead to less censorship. Blocking tweets in only certain countries is better than deleting them worldwide, she said. "I think the proper target of people's outrage ought to be the countries that do the censoring," she said. Even in countries subject to Twitter's nation-specific blocks, users can likely circumvent the blocking by using Tor anonymizing software, she said.

Twitter hasn't yet used its new ability, but said "when we are required to withhold a Tweet in a specific country, we will attempt to let the user know, and we will clearly mark when the content has been withheld." Deleting tweets is nothing new. What is new is Twitter's ability to prevent people in only one country from seeing specific tweets.

Chilling Effects is designed to inform people about their online rights and help them navigate a legal process that the groups behind the site believe has a "chilling effect" on legitimate Internet activity. "Anecdotal evidence suggests that some individuals and corporations are using intellectual property and other laws to silence other online users. Chilling Effects encourages respect for intellectual property law, while frowning on its misuse to 'chill' legitimate activity," the group says on its website. (One porn site and copyright holder, by the way, made the interesting argument in 2010 that publishing certain takedown notices on Chilling Effects was itself a copyright violation, because the notices contained copyrighted images.)

It is clear that many of the Twitter takedown notices are aimed at bot-like accounts that continue to link to pirated material even after specific takedown requests are granted. Others are just casual Twitter users, including one who complained about the DMCA after one of her tweets was deleted because of a link she posted to the Pirate Bay.

The tweet in question linked to a piece of sheet music that costs $105, and the takedown notice sent to Twitter reads: "We ask that the Twitter public not be encouraged to visit infringing sites. Kindly remove this tweet. We have contacted piratebay.com as well."

Twitter has a page for reporting copyright infringement available for copyright owners and authorized representatives of copyright owners. It also contacts Twitter users after complaints are filed. "If we remove or restrict access to user content in response to a notice of alleged infringement, Twitter will make a good faith effort to contact the affected account holder with information concerning the removal or restriction of access, along with instructions for filing a counter-notification," Twitter says in its copyright and DMCA policy.

Twitter users targeted by DMCA takedowns can file counter-notices by responding to Twitter's e-mail notification. Counter-notices are forwarded to the copyright holder who issued the takedown request. If the copyright holder does not respond within 10 days, Twitter may re-publish the deleted tweet. But within the 10-day period, the rights-holder can seek "a court order to prevent further infringement of the material at issue," Twitter says.