Software developer Mozilla has announced it is joining the protest against US anti-piracy laws by redirecting traffic from and for 12 hours.

As part of the re-direction, which will begin at 1pm GMT today (Wednesday January 18) web users attempting to access these sites will be greeted with a black web page emblazoned with a 'call to action' message that Mozilla says aims to raise awareness of the issues with the anti-piracy proposals.

The Stop Online Piracy Act (SOPA) and the Protect-IP Act (PIPA) are currently going through US Congress. If these become law, copyright holders and US Judges will have to right to shut-down websites if they believe they offer illegal access to copyrighted material such as music and movies. At present, under existing US law, a website owner must simply remove illegal content when they notified by the copyright holder. However, the new acts put the onus on the website itself to check material does not infringe copyright.

"SOPA makes all of us potential criminals if we don't become the enforcement arm of a new government regulatory and policing structure," said chair of the Mozilla Foundation, Mitchell Baker, in a blog.

"Assume there's a corner store in your neighbourhood that rents movies. But the movie industry believes that some or even all of the videos in that store are unauthorised copies, so that they're not being paid when people watch their movies. What should be done?," questioned Barker

"SOPA/PIPA don't aim at the people trying to get to the store. SOPA/ PIPA don't penalise or regulate the store itself. SOPA and PIPA penalise us if we don't block the people trying to get to the store."

A number of websites including Wikipedia and Reddit have put a black-out in place today in a bid to raise awareness of the problems the acts could cause.

Mozilla said the search functionality will in no way be altered by this action.