Copyright law isn't so elementary, my dear Watson. But, in 2023, it gets a lot easier for Sherlock Holmes. On New Year's Day, Arthur Conan Doyle's final original work featuring the legendary character, The Case-Book of Sherlock Holmes, enters the public domain.
This copyright expiration puts a long-running legal debate to rest. For years, the Doyle estate has argued that although the early works featuring Sherlock Holmes are public domain, the fact that later books written by Doyle are not means the character remains under copyright. Now that The Case-Book has entered the public domain, that argument is moot. Anyone can now write their own Sherlock Holmes stories or use the character in any other way without fear of copyright infringement.
Additionally, the entry of Doyle's final Holmes work into the public domain means anyone can publish those stories and profit from that publication without fear of legal ramifications. Doyle's first Holmes novel, A Study in Scarlett, was published in 1887 and first entered the public domain on January 1, 1981. However, an addendum to U.S. copyright law was passed in 1995, and Sherlock went back under copyright until January 1, 2000.
We should expect to see a rerun of the Holmes debate next year, but for Mickey Mouse. The first appearance of that character, Steamboat Willie, enters the public domain on January 1, 2024. For many years, Disney has lobbied to prolong their copyright on the iconic mouse, and the company is likely to use every tool at its disposal to extend its hold on the intellectual property.
Source: The Verge