Here is a quote about copyright and sound recordings pre-1972, which represents the vast majority of songs I have ever featured on my Web site. When it refers to common law or state statutes, does this refer to piracy? The term does not seem to apply here.
"NOTE: Sound recordings fixed before February 15, 1972, were generally protected by common law or in some cases by statutes enacted in certain states but were not protected by federal copyright law. In 1971 Congress amended the copyright code to provide copyright protection for sound recordings fixed and first published with the statutory copyright notice on or after February 15, 1972. The 1976 Copyright Act, effective January 1, 1978, provides federal copyright protection for unpublished and published sound recordings fixed on or after February 15, 1972. Any rights or remedies under state law for sound recordings fixed before February 15, 1972, are not annulled or limited by the 1976 Copyright Act until February 15, 2047.
Under the Uruguay Round Agreements Act, effective January 1, 1996, copyright was restored for certain unpublished foreign sound recordings fixed before February 15, 1972, and for certain foreign sound recordings originally published without notice. For further information, request Circular 38b, "Highlights of Copyright Amendments Contained in the Uruguay Round Agreements Act (URAA)."
Re: Agreements with Swallow and La Louisianne Records
If you want to check whether they got the copyright or not you´ll need lawyers, specialized attorneys.
Maybe a crazy idea, anyway:
Many of the big (international) law firms – I was working for an english one a couple of years – do pro bono work and contribute pro bono hours each year. Maybe there is an attorney who is interested in Cajun music……