An 1895 law restricts the “sale, possession or shipment of imitation butter and bans yellow-tinted varieties. Those dealing contraband dairy products can be fined up to $100 and jailed for up to a month.”
And if you’re caught selling with 100 feet of a school? Death penalty.
Could not come up with a “When things are outlawed” headline for this. “When margarine is decriminalized, only criminals will have margarine”? Too slippery
Collateral Damage 
That law was still on the books in Minnesota when I was growing up in the 1940s and 1950s. Uncolored, white margarine came in plastic bags with a little bubble of coloring. You squeezed the bubble to break it, then you kneaded the bag to spread the color around. Presto, you had butter-colored margarine. But as Covert Bailey would say, “It’s still fat.”
If you think this is unique to MN, check out this article… “Margarine was Prohibited in Canada from 1886 to 1948” http://canadianhistory.suite101.com/article.cfm/we_want_margarine
The farmers think yellow margarine is false advertising, because when it’s white, it looks like Crisco. Many of my wife’s cousins live in Canada and they don’t seem to mind margarine being white or buying milk in plastic bags.
We’re eating some sort of yellow soy-based spread these days and I’ve gotten used to it. No problemo. I wouldn’t mind if it were green, but then again, maybe the guacamole industry would go after them for an infringement of their color, in the event it was a similar shade?
Just think of the “revenue” they would lose if the law is repealed, although it might be offset with the large amounts of open beds in their jails!