At 12:01 am on January 1st, while some were watching celebrated news anchors doing tequila shots live from Times Square, something amazing happened:  for the first time in more than two decades, a significant cache of works fell into the public domain in the United States - specifically, most works that were originally published in 1923 in the United States and that remained protected under Copyright Law.  (There are some exceptions.)  Why the dry spell?  In 1998, Congress passed the Sonny Bono Copyright Term Extension Act which increased the duration of copyright protection for works published between 1923 and 1977 from 75 years to 95 years.  The net effect was that the flow of works into the public domain ceased completely for 21 years.  According to several websites, the works from 1923 that we are now free to use without fear of copyright infringement claims include Robert Frost’s poem "Stopping by Woods on a Snowy Evening," the quirky song "Yes! We Have No Bananas," and Cecil B. DeMille’s film The Ten Commandments.  (Not (sigh) the 1956 version of The Ten Commandments, starring Charlton Heston as Moses.)

This is only the beginning:  unless Congress intervenes, from now on, on January 1st of each year, the public domain in the U.S. will be further enriched with those works published 95 years earlier.  Some really good stuff is on deck to fall into public domain.  As the New York Times notes, "over the next few years, the impact will be particularly dramatic, in part because the 1920s were such a fertile and experimental period for Western literature, with the rise of masters like F. Scott Fitzgerald, William Faulkner, Ernest Hemingway and Virginia Woolf."  And, just around the corner (in 2024), the copyright in the original incarnation of the Mickey Mouse character (from the 1928 film Steamboat Willie) will expire.  

In the short term, we can expect some pretty pedestrian uses of these works.  (I'm envisioning snow globes with lines from Frost's poem.)  In the long run, however, I am excited to see how authors, filmmakers, musicians and other creative types breath new life into these old works.  

A few things to keep in mind, however, before you go crazy ripping and mixing songs, books and films from 1923:

• While works from 1923 may be public domain in the United States, they may remain subject to copyright protection in other countries.  For example, a work published worldwide in 1923 by an Italian author who died in 1980 could be protected in Italy and other countries. 
• Only the version of the work, as originally published in 1923, is in the public domain.  Subsequent editions, arrangements, and embellishments of the work may include elements that remain protected under copyright law.  For example, if Ariana Grande were to record a new version of "Yes! We Have No Bananas," any new material she adds (such as original lyrics or melodic interludes) are potentially subject to copyright protection.  (And, of course, Ms. Grande’s sound recording is also subject to copyright protection.)  See Klinger v. Conan Doyle Estate, Ltd.
• We can anticipate that certain rights holders, in certain instances, may try to use trademark law to prevent (or at least limit) the use of their works even after copyright has expired - at least in cases where they believe that consumer confusion is likely as to whether the rights holder was the source of the work or goods in question.  (Mickey Mouse is protected not only by copyright law, but also by trademark law.)  How successful those efforts will be remains to be seen, especially in light of the Supreme Court’s decision in Dastar Corp. v. Twentieth Century Fox.  
• Figuring out the public domain status of a work can be a little tricky.  This handy table is a good starting place to begin any inquiry.