when does a patent enter the public domain
Public domain In most countries the term of rights for patents is 20 years, after which the invention becomes part of the public domain. In the United States, the contents of patents are considered valid and enforceable for 20 years from the date of filing within the United States or 20 years from the earliest date of filing if under 35 USC 120, 121, or 365(c).[54] However, the text and any illustration within a patent, provided the illustrations are essentially line drawings and do not in any substantive way reflect the "personality" of the person drawing them, are not subject to copyright protection.[55] This is separate from the patent rights just mentioned.