Copyright protects original works of expression fixed in a tangible format, for a limited duration. When the term of protection expires, the work falls into the public domain, and anyone may legally copy it.
Copyright protects only original works of human authorship. The legal requirement of originality as it relates to copyrightable expression, however, does not map exactly to our normative understanding of that word. When we describe something as “original” we usually mean it is unique, one-of-a kind, the first instantiation — e.g., “an original solution to a problem.”
Copyrightable expression may be original, however, even if it is not the first instance of that expression, as long as it originated from an author’s intellect. The chances of the same protectable expression originating independently from two or more authors is extravagantly unlikely, though theoretically possible when working with brief and highly structured genres like haiku.
Those working in life sciences and pharmacy often independently simultaneously arrive at the same “breakthroughs”. But the valuable information that these breakthroughs (new pharmaceuticals, medical devices, etc.) contain typically is not copyrightable expression that more than one party might legally own. Accordingly, “breakthroughs” in these fields are usually protected instead by Patent and Trade Secret.
In the United States (and many other countries) a work of original authorship can be protected by copyright only if it has been fixed in a tangible medium of expression. While most human expression — conversations, gestures of signed languages, informal musical performances, etc. is not fixed, expression that has — or may have — economic value, like a novel, a song, a video game, typically is fixed.
While we are unable to perceive a musical work from a CD on which its performance is encoded, a CD player can render this code into sounds that communicate the musical work, and therefore it has been fixed in the CD. On the other hand, if I write a novel using disappearing ink, unless readers are informed of a method by which to make the text reappear, the novel is not fixed even if the text was temporarily visible.
The first U.S. Copyright Act of 1790 provided authors a term of protection of 14 years, which could be renewed if the author was living at the end of the initial term.
Over the past 230 years the term of copyright protection has inexorably expanded. Today it lasts from the date it was created for the life of its author, plus 70 years after the author’s death. Many consider this dramatic prolongation distorts the U.S. Constitution’s requirement that intellectual property protections be granted for “limited times”.
Many copyrightable works have more than one author: Broadway musicals, popular songs, scholarly articles, etc. The copyright term for what are called “joint works” lasts 70 years following the death of the last living author.
If the copyrightable expression is created by an employee within the scope of his employment it is a “work made for hire,” and is protected for the shorter of 95 years from the date of publication, or 120 years from the date of creation. Suppose you were a copywriter (not copyrighter!) at an ad agency charged with drafting the script for a TV advertisement for Pfizer’s “Celebrex”. This drafting work is obviously within the scope of your employment, and your employer (ad agency) would own any copyright adhering to your work. If, however, your agency’s ad, was commissioned by Pfizer, the producer of Celebrex, Pfizer would have required your agency to assign (legally transfer the ownership in writing) to it the copyright protecting the ad.
Pfizer’s 120-years copyright term would begin to run when you created the ad (i.e. fixed it in a tangible form, most likely a Word document stored on your computer’s hard drive). If Pfizer decides to air the ad at any point within 25 years following the date you created it, the copyright term would be shortened to 95 years from the date the ad was aired. If Pfizer wanted to obtain the longest possible term of protection, it would wait 25 years before airing the ad, which would then be protected for 120 years. Of course 25 years after its creation the ad would likely have no commercial value.