Some magic dealers claim intellectual property rights to certain magic tricks that were invented many decades ago by long-dead magicians and sold to these dealers. In other areas of society, ownership issues are disputed and controversial (example: land ownership). Were there such controversial discussions on the issue raised here? If so, where? Or are there people here with critical views who could describe their views? Many thanks for any information/viewpoint. I am specifically concerned here with magic tricks that were invented a long time ago by magicians who have since died. One example is the fantastic magic trick invented by magician Werry (1925 - 2000), probably in the 1950s, in which a forced card is produced from a hat using a rope. It could be argued that the gentlemen agreement that apparently only the dealer who bought the trick is allowed to produce the trick for an unlimited period of time is not in the interests of all people, but primarily in the financial interests of those who enter into the gentlemen agreement.

Assume the secret is written down, which would make it fall under copyright in the same way recipes and theatrical performances are copyrighted the moment they were first written down.

Keep in mind the venue of this discussion. And this can be discussed as a supply/demand question.

The good of the market versus the good of the art... or the market for art supplies.

TL;DR - the spice must flow.

Independent of any one persons views the issue of enforcement comes to mind immediately. How? How do you think it can be enforced?

I don’t say that to be flippant or sarcastic. Generally if an agreement is not in place (In America.) the courts are hesitant to try to put on there. Since everyone is pretty long dead it wouldn’t even be really possible anyhow. How would international enforcement even happen? Gentlemen’s agreements are really only going to work between them, and not all the time.

It is a long and winding road you are talking about.

"Assume the secret is written down, which would make it fall under copyright"

This is not an accurate description of the legal situation. In principle, ideas/secrets are not protected by copyright.

Patent infringement then... Not a lawyer:-)

"Patent infringement then..."

Sorry, but that's not true either. The following text provides good information about the legal situation. However, my question was aimed at the ethical aspect of the topic.

Secrets Revealed: How Magicians Protect Intellectual Property without Law
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1005564

Ethics in magic?

Good luck.

As a better writer than yours truly put it: It's like walking someone else's dog.