In one of the first cases of its kind, a judge in the US has ruled that two news organisations have infringed on the copyrights of photographer Daniel Morel, because they used photos he posted to Twitter without prior permission.
Morel took a number of photographs of the aftermath of the earthquake in Haiti in 2010 and through a long process they found themselves on Agence France-Presse and The Washington Post. When questioned AFP said that all Twitter photos are basically fair game, which the judge clearly didn't agree with.
Of course this is just a one-off ruling and maybe shouldn't be seen as a definitive rule that if you lift something from Twitter you'll be taken to court. But having said that we don't advise you to go ahead and start stealing photos from Twitter left, right and centre, especially if it's for commercial purposes, because it's clear some people are really possessive over the content they upload to the site and will take action if they're feeling angry enough.
The Verge asked Twitter what the official stance on all of this is, to which the team responded, "as has always been our policy, Twitter users own their photos."