Which is authoritative: Ban List or Gatherer?
MTGCommander.net is the authoritative reference for all things commander.

Says who?

First, a little history.

According to this article, Adam Staley created the format. He shared it with Sheldon Menery, a retired Level 5 Judge, who popularized the format by inviting judges at tournaments to play. Over the next few years, the format spread from judges to the common player.

Gavin Duggan, who is a member of the Commander Rules committee along with Sheldon Menery, is also the creator of MTGCommander.net. When the rules committee bans a card, it shows up there first.

Wizards of the Coast catches on

But they wanted to avoid using the trademarked "Highlander" in the name (which could lead to a lawsuit), and so Wizards changed the name to "Commander". Wizards maintains the Gatherer and their own banned list for MTGO. Their list links to MTGCommander in the opening paragraph!



We like rules

If that wasn't convincing enough, there is actually a rule that acknowledges MTGCommander as the source of "additional resources" (emphasis mine):


  903.1. In the Commander variant, each deck is led by a legendary creature designated as that deck’s commander. The Commander variant was created and popularized by fans; an independent rules committee maintains additional resources at MTGCommander.net. The Commander variant uses all the normal rules for a Magic game, with the following additions.