The only regulation that I think really addresses that is a law that prevents a registered referendum advertiser from promoting or opposing, directly or indirectly—that's the wording you'll often hear with election advertising—the election of a candidate or a party. They can make only statements that promote a particular response to the referendum ballot in their advertising.
So it's unlimited expenses for referendum advertisers. But first of all, there weren't that many referendum advertisers who registered. Secondly, from what I've seen, they didn't spend nearly as much money as was the case in 2005. Most of the money went in support of these two umbrella groups, which were each receiving half a million dollars from the government to promote the debate.