The duration of copyright has changed several times as Congress has updated the law. Currently, you can generally presume that a work copyrighted less than 95 years ago is still covered by the law. Here are the basics.
Several categories of material are generally not eligible for federal copyright protection. These include among others:
- Works that have not been fixed in a tangible form of expression that exists for more than a transitory duration. It does not have to be readable by the human eye (e.g. content stored on CDs or on a computer hard drive)
- Titles, names, short phrases, and slogans; familiar symbols or designs; mere variations of typographic ornamentation, lettering, or coloring; mere listings of ingredients or contents
- Ideas, facts or discoveries
- Recipes, unless they include substantial literary expression in the form of an explanation or directions, or when there is a collection of recipes as in a cookbook
- Works consisting entirely of information that is common property and containing no original authorship (for example: standard calendars, height and weight charts, tape measures and rulers, and lists or tables taken from public documents or other common sources)
- Works of the federal government, but works created by state or local governments may be protected.
- Works whose copyright has expired