Jeffrey Zeldman’s You cannot copyright a Tweet:
Contrary to popular belief and Twitter’s terms of service, you cannot copyright a Tweet. Under US law, copyright is granted on publication to “original works of authorship” finalized in “fixed forms of expression” but this does not extend to names, titles, or short phrases (PDF).
As messages sent via Twitter cannot be longer than 140 characters, they cannot be copyrighted.
I disagree. You can fit a good two sentences into 140 characters. Many poems, presumably protected by copyright, are shorter than that. A unique, two-sentence creative work that happens to be under 140 characters is probably copyrightable, or at least a gray enough area to cause any copyright fight not to be worthwhile enough to fight. (update: Legal analysis, thanks David Chartier)
For internet-based “copying”, the DMCA is most of the problem.
I hereby copy one of Zeldman’s Twitter posts:
The underwear said “Friday” but it was Wednesday. I said, “We won’t tell the underwear police.” Now she’s afraid of the underwear police.
Now, suppose Zeldman objected to this copy of his creative work. (I know he said he wouldn’t, but suppose he did.)
If he sent a DMCA takedown notice for this post to The Planet, I would be forced to remove his content from this post. Even if I wanted to argue that his complaint was invalid and that this was not a copyright violation, the content would be taken down for up to three weeks for “review”. After reviewing it, The Planet’s legal staff would side with Zeldman since it’s a gray area and they don’t want to risk the liability, and the content would remain down.
The validity of the copyright complaint is irrelevant, as long as it might be copyrightable, because at no point is anyone willing to test it.
If the copy was for a purpose not covered by the DMCA, like making a Twitter book, he could just send a legal warning letter to the publisher. They wouldn’t want the hassle and potential expense of fighting it, so they’d make the author remove the specified content without a second thought.
In copyright, if it’s a gray area or it’s arguable or “it should be fair use” or “it might be fair use”, it’s effectively copyright-protected for anyone who doesn’t have a large amount of time and money with which to argue otherwise.