Notes Wikipedia: “Ancient Greece Athenaeus, writing in the third century CE, mentions that in 500 BC, in the Greek city of Sybaris (located in what is now southern Italy), there were annual culinary competitions. The victor was given the exclusive right to prepare his dish for one year.”
It is no wonder they had such a law. It is obvious that without it no one would have an incentive to come up with new recipes. This is why, in the modern world, in which there are no copyrights or patents on food dishes, we have no innovation in food at all. Unfortunately, we are stuck repeating the glories of 2500 year old Greek cuisine, which flourished for a brief time under the benevolent guidance of the government.
Update: see also Michael Witty, “Athenaeus describes the most ancient intellectual property” (2018)