In the United States and most other countries, unless you are the one who created the backup from your own legally obtained copy. The Digital Millennium Copyright Act (DMCA) in the US only permits the creation of a backup copy by the owner; it does not authorise downloading someone else’s copy.

: A popular repository specifically for 3DS and DSiWare content. They host the North American version as a direct download (roughly 13.84 MiB).