On the Forums.usa.canon.com website, a user "Kronie" asked the following question :
"Does Canon honor the USA warranty if I buy the EOS-5D Mk III from a non-authorized dealer?"
Canon Forum Moderator, "Naomi" responded :
As long as the EOS 5D Mark III was purchased New, In box, you should have the same warranty coverage. To help you out, we've included a link to the Service and Support page on our website for the Canon EOS 5D Mark III camera. Click "Warranty Terms" under "Service & Repair", and you'll find a link to the full camera warranty on this page.
Hope this helps!"
Note : There is no official documentation from Canon substantiating this moderator's claim that Canon will honor warranty repairs for purchases made from non-authorized dealers. However, there are numerous reports that Canon is relatively loose when interpreting its own warranty repair policies. In fact, a friend of mine recently bought a used EOS-1Ds Mk III camera with only about 25,000 actuations and he took it in for service. Canon checked, cleaned and made minor repairs to the camera, all at no charge.