Originally Posted by
kedawa
There is a scenario where you would in fact be violating copyright.
You can authorize one console per year to run XBL content without having to be signed in with your account, with the limitation that XBL will de-authorize them once they are authorized for another console. So, basically, you could load up one console per year with all of your digital downloads and sell it, and they will function just fine so long as the buyer doesn't connect to XBL. As a result, you'd be selling multiple copies of something you only bought once, which is essentially piracy, and you'd be selling something that will become void the moment the buyer decides to go online.
As far as the legality of selling your account goes, obviously an EULA or ToS can't contravene local laws and consumer rights, and it's not as if the swat team is going to kick in your door even if you are doing something 'wrong', but as far as eBay and the like are concerned, big content is always right.