The symbol was introduced into United States copyright law in 1971, when the US extended limited copyright protection to sound recordings. The United States anticipated signing onto the
Geneva Phonograms Convention, which it had helped draft. On October 15, 1971, Congress enacted the
Sound Recording Act of 1971, also known as the Sound Recording Amendment of 1971, which amended the
1909 Copyright Act by adding protection for sound recordings and prescribed a copyright notice for sound recordings. The Sound Recording Act added a copyright notice provision specific to sound recordings, which incorporated the symbol prescribed in the Geneva Convention, to the end of section 19 of the 1909 Copyright Act: The provision that currently governs it is in , the codification of the
Copyright Act of 1976. That section provides for the a non-mandatory copyright notice on sound recordings: :If a notice appears on the phonorecords, it shall consist of the following three elements: ::(1) the symbol ℗ (the letter P in a circle); and ::(2) the year of first publication of the sound recording; and ::(3) the name of the owner of copyright in the sound recording, or an abbreviation by which the name can be recognized, or a generally known alternative designation of the owner; if the producer of the sound recording is named on the phonorecord labels or containers, and if no other name appears in conjunction with the notice, the producer’s name shall be considered a part of the notice. ==Encoding==