When you get the search results, click "search on date"
www.amnesty.org/results/is/eng?queryType=0&searchIn=0&query=iran&start=1&num=10&max=25&sortBy=date
www.tinyurl.com/crx58
(BTW, I was asked by the moderators a while back not to post "clikable" links, as this points back to FR).
Thanks, that's good stuff.