Transfers between the various EU regions has been possible, and when the Brazilian server went live they moved them.
As for the legal reasons, it isn't something controlled by Riot. They are Government controlled, partly due to the fact that the Euro is worth more than the US dollar so you have taxation and exchange issues.
A long while back one of the guys at Riot gave a more detailed response on it, and it was nuts to make it happen.
Anyway, thanks for the reply in this thread. I really think that this is very nice when after 345 pages of bumping and begging for the help somebody from RIOT has spoken.