British Prime Minister David Cameron has passed a law banning "Rape Porn" or porn depicting acts of rape, be it videos or images, simulated/fantasy rape or not. I'm not too sure if it applies to furry stuff, but it's probably a good idea to be on the safe side and blacklist the rape tag just in case if you live in the UK or Wales (Scotland has already had this problem it seems) because if you are caught with rape porn, you can face a sentence of 3 years in jail.
More details in these articles here:
http://www.businessinsider.com/people-with-rape-porn-in-the-uk-could-get-jail-time-2013-11
Updated by EDFDarkAngel1