Actually, it's not.
Not a lawyer, but had to take respective classes and have to apply them to software, among others.
There is 3 IP protection mechanisms:
from
https://www.stopfakes.gov/:
- A U.S. utility patent, ... is generally granted for 20 years from the date the patent application is filed; however, periodic fees are required to maintain the enforceability of the patent. ...
- A U.S. trademark generally lasts as long as the trademark is used in commerce and defended against infringement.
- Copyright protection is for a limited term. For works created after January 1, 1978, copyrights last for 70 years after the death of the author. ...
For example, Spyderco/Sal patented the Spydie-hole, and after expiration of the patent has trademarked it. A patent is protecting a device in the "loosest" way, a mechanism with one or more implementations (like the Spydie-hole, a knife lock, pocket clip, etc.) will be protected from being copied
conceptually.
Copyright protects designs/text/art/etc. from being copied more or less verbatim, and these copies being used commercially. For example, you can go to the library, photocopy a page of a book, and legally use it for your own purpose. But you can not publish the copy and make money. In other words, a knife design that is slightly different than another one, is not a copyright violation.
Roland.