A treasure trove of recordings made in the 1950s is about to slip out of copyright. “Copyright protection lasts only 50 years in European Union countries, compared with 95 years in the United States, even if the recordings were originally made and released in America. So recordings made in the early- to mid-1950’s — by figures like Maria Callas, Elvis Presley and Ella Fitzgerald — are entering the public domain in Europe, opening the way for any European recording company to release albums that had been owned exclusively by particular labels.”