As stated by 188.8.131.52, I always thought it was a jinx that backfired, as opposed to a jinx that causes things to backfire; if my memory serves me correctly, 'backfiring jinx' was not capitalised. If it was a jinx that backfired rather than a jinx that causes things to backfire, is it possible that there are 'backfiring charms' and such? If so, I presumed that Ron Weasley would have had this happen to him in Chamber of Secrets. This theory is supported by the fact that the Trading Card designated to depicting Ron's malfunctioning wand is titled "Backfire!". Hunnie Bunn (talk) 17:37, July 8, 2012 (UTC)
It doesn't take a genius to see that the theory for this page is a load of balderdash. It is outright ridiculous for this page to exist! Come on, what are we hesitating for? There is no decent proof for this being an actual jinx. Of course, all spell types can backfire under certain circumstances, so this should be no exception. The Trading Cards have always been a little bit funny with canonality, and besides, if it reads "Backfire!" that seems obvious to me that the card is refering to any general spell backfiring. Let's just delete it.
We need to be rid of this page
I'm absolutely certain that when the words "backfiring jinx" were in the books, they were not refering to a particular type of jinx casted, but rather an unspecified jinx that happened to be physically "backfired". Therefore, I highly suggest that this entire page should be deleted for its irrelevency.