The US copyright office will permit mobile phone subscribers to unlock their phones, allowing them to be used by rival network providers.

It's a right that's taken for granted in most of the GSM world, where there's little operators can do to stop it.

But US carriers, being the enlightened souls that they are (lowest form of wit - ed.) used fear created by the 1998 Digital Millenium Copyright Act to prevent unlocking. The DMCA outlawed the circumvention of technological protection measures on copyright works - with few exemptions. It promised to permit the US Congress' copyright office to review these exemptions from time to time.

Now, in its third review of permissible DMCA exemptions, the US Congress' copyright librarian has lifted the fear of prosecution from unlockers:

"Computer programs in the form of firmware that enable wireless telephone handsets to connect to a wireless telephone communication network, when circumvention is accomplished for the sole purpose of lawfully connecting to a wireless telephone communication network."

Another new exemption has been introduced for security researchers investigating DRM on sound recordings, or videos with sound recordings, that are distributed on CD.

You can thank hapless Sony, who distributed the notorious "rootkit"-style DRM last year, for raising the profile of that issue.

The measure permits researchers to circumvent copyright protection measures - "...when circumvention is accomplished solely for the purpose of good faith testing, investigating, or correcting such security flaws or vulnerabilities."

That's the end of the good news.

When the last review of DMCA exemptions took place in 2003, researcher Seth Finkelstein won an exemption for similar researchers, and academics, investigating censorware blacklists.

(This is a subject close to our hearts: in 2001 a censorware company blocked access to The Register for millions of readers because it didn't like a story we'd written about one of their products.)

Until Finkelstein's exemption, it was illegal to figure out what sites the censorware companies were blocking - and they didn't have to tell you. The "filter" vendor was cop, jury and hanging judge.

(You can read the new exemptions here, and compare them to the 2003 list).

Seth decided not to pursue the issue this time round, citing the stress of facing legal threats and personal harassment in his lonely crusade - as he explained here.

Amazingly, no one amongst the law schools, think tanks and "activist" community - who rarely miss the opportunity to talk about free speech - stepped in to take his place and challenge the blacklist companies. As a result, the exemption has been lost.

Seems like it's easier to talk about freedom, than actually fight for it.®