Ah... The questions.
DeCSS is a tool written by a private individual (Jon Lech Johansen of Norway) to decrypt the CSS encryption found on DVDs. Now, the DVD CCA (DVD Copy Control Association) is fighting to have DeCSS removed from existance. Obviously, because it was distributed over the internet, DeCSS has found it's way to every nook and cranny of the planet, so they're using the RIAA's approach of 'Sue everyone you can find who has a copy of the software', and like the RIAA, they're having trouble aniahlating it. But the reason I write is much more deep: What rights do they truly have in the matter.
Jon, when he wrote the program, pretending he where an American citizen, did not at any time copy some segment of code from the DVD CCA. So officially, he is not in violation of the copyright law. Now as for the matter of reverse engineering... You come to the fact that it's done regularly in industry (think Malt-O-Meal and IBM PC Clone.) So if the DVD CCA where to get reverse engineering banned, they would be cutting their own throats. So really the program itself is perfectly legal (See Title 17 Chapter 12(1201)(f) for the exact wording) because he was making a linux DVD player (Which was not availible prior to his efforts.)
But as for the way DeCSS is used, that's an entirely different matter. Copies made for illegal distribution or 'personal financial gain' (which includes not having to buy the DVD) are illegal. And although it was not the intent of Jon, it has clearly become one of the leading uses of DeCSS. Up until 1998, these would have been legal, but since the Digital Millinium Copyright Act of 1998, 'circumvention of technological measures' is illegal (See Title 17 Chapter 12(1201)(a)) (which explains why there are so many copy protection 'cracked' C64 games...) So I don't think that the DVD CCA has any rights at all to control the linux DVD player, but perfect right to control any version of DeCSS used directly for the purpose of making duplicate, unzoned DVDs.
The only thing that bothers me is that most of the exemptions made for the purpose of home entertainment do not apply to movies, but do apply to music...
Hmm... More copyright Law goodness