In the United States, songs enter the public domain 95 years after the death of the last surviving author. Louis Armstrong performed and popularised the song, but he did not write it. The songwriter of "St. James Infirmary" is unknown, making the song a traditional folk song. As a traditional folk song, it is considered public domain in the United States.
In Canada, copyright for musical works lasts 50 years after the death of the author, and thus songs released before 1972 have entered the public domain. "St. James Infirmary," recorded by Louis Armstrong in 1928, is in the public domain in Canada.
In the European Union, copyright protection lasts for 70 years after the author's death. Louis Armstrong's recording of "St. James Infirmary" is in the public domain in Europe.
However, in Brazil, the copyright term is 70 years after the death of the author. Since "St. James Infirmary" is a traditional folk song with no known author, the copyright term in Brazil can potentially be calculated based on the earliest published arrangement or recording of the song. If such a publication or recording occurred after 1953, the song may still be protected by copyright in Brazil.