When margarine when it was invented, it cut into the butter market. The dairy lobby begged Congress for help and I got it in the form of a federal tax on margin of one quarter of a cent per pound on white margarine and 10 cents per pound on yellow margin. Obviously, since people were used to yellow butter, white margarine was unattractive and less competitive. This discriminatory tax on margarine, especially yellow margin, was challenged. Would such a tax be improper?