The Code of Federal Regulations, which govern ‘standards of identity’, was created in 1938 specifically to prevent companies from selling fake food using established names and duping customers into thinking they got one thing while spending money on another.

So no one should be able to sell you fake mayonnaise made from vegetable paste. Hampton Creek has wanted to do just that. Vegetable Paste is obviously a harsh characterization but it is a vegan substitute for mayonnaise so it has no eggs. Yet they still want to be called mayonnaise. The FDA and competitors disagreed. Unilever, which owns  Hellmann's and other brands like Ben&Jerry's plus too many products to list) objected. A corporation would ordinarily not want an exemption for a fake product because it could be cheaper, but that is not the case with "just Mayo", they are selling self-identification so they will be more expensive. Instead, Just Mayo was “one of the most blatant violations of the standard-of-identity rules that I’ve seen in a long time,” according to a former head of the FDA’s office of food labeling.

Despite their vegan (translation in a two-party system: Democrats) approach, they had managed to get some libertarian support the way raw milk proponents did - by asking if government should be choosing what people can buy. And by alleging the Obama administration bought off bloggers and Whole Foods.

None of that really worked, so they redefined "just" on the new label, which satisfied the FDA. It is now an adjective that means "guided by reason, justice, and fairness."  So it is not 'just like mayonnaise' or analogous to 'only mayo', it is mayo substitute with a dose of vegan values; the self-identification is more important than the product. 

Watch below as similar self-identification redefines a vegetable loaf as a cake, which annoys pretty much everyone who is not a vegan: