Hackers are skating close to the edge of the law in protest over legislation such as the Digital Millennium Copyright Act (DMCA), which they claim is eroding their rights to make "fair use" copies of media.

Two weeks ago at the O'Reilly conference, open source expert Bruce Perens had his attempts to break the DMCA live on stage thwarted by employer Hewlett Packard (HP). But this did not stop a similar attempt by another hacker at the DefCon conference last week.

On Saturday afternoon, speaking at the legendary DefCon hacker conference in Las Vegas, Adam Bresson, owner of a network consultancy, gave a presentation on the identification and bypassing of common media protection systems.

His family were in the audience as his witnesses, and his talk was videotaped in case anyone pulled him up for breaking the DMCA.

Bresson was quoted by the Hindustan Times saying that there was a fine line between creating copyright-breaking technologies and demonstrating them, and the fact that he had not been arrested at the convention appeared to show that he had not crossed it.

This time last year, Russian programmer Dmitri Sklyarov was arrested at DefCon for demonstrating a technology he created that was capable of cracking the copy protection on Adobe's eBooks.

Although Sklyarov was freed, his employer, ElcomSoft, now faces criminal charges.

Straight after Bresson's presentation - in which he demonstrated breaking different protection methods on DVDs, video games and CDs - Joe Burton, defence counsel for ElcomSoft, gave an update on the Adobe case.

Commenting on the presentation, Burton said that he believed Bresson stayed on the right side of the law by demonstrating and not creating or distributing the technology.

But he warned that there were still prosecutors out there who would take on such a case.

The DMCA has become more of a target for the security industry recently as it is increasingly used by companies as a stick with which to beat legitimate research.

Last week HP threatened a small security company, SnoSoft, with breach of the DMCA after it published details of a vulnerability in its Tru64 operating system.