Is it illegal for Wisconsin restaurants to replace butter with margarine, unless a customer requests it?

A section of Wisconsin law under the heading "oleomargarine regulations" states:

“The serving of colored oleomargarine or margarine at a public eating place as a substitute for table butter is prohibited unless it is ordered by the customer.”

To protect its farmers and butter, America's Dairyland banned yellow margarine in 1895, meaning it was legally available only in white, according to the Hoard Historical Museum and National Dairy Shrine in Fort Atkinson, Wisconsin.

The law also generally prohibits serving oleomargarine or margarine to students, patients or inmates of any state institution as a substitute for butter. Violators can be fined between $100 and $500, imprisoned up to three months, or both.

Many Wisconsinites in the 1950s and ‘60s crossed state lines to buy yellow margarine. Wisconsin’s color ban ended in 1967 — but the ban on serving margarine at restaurants unless requested remains.