'When Irish Eyes Are Smiling' was written in 1912 by Ernest R. Ball, Chauncey Olcott, and George Graff, Jr., each of whom was under contract to P. On August 12, 1912, P applied for and obtained the copyright of the song. On May 19, 1917, Graff and P made a further agreement, under which, for the sum of $ 1,600, Graff assigned to P 'all rights, title and interest' in a number of songs, including 'When Irish Eyes Are Smiling.' P was given an irrevocable power of attorney to execute in Graff's name all documents 'necessary to secure to P the renewals and extensions of the copyrights in said compositions and all rights therein for the terms of such renewals and extensions.' Graff agreed that 'upon the expiration of the first term of any copyright,' he would execute and deliver to P 'all papers necessary in order to secure to it the renewals and extensions of all copyrights in said compositions and all rights therein for the terms of such renewals and extensions.' The agreement was duly recorded in the Copyright Office. On August 12, 1939, the first day of the twenty-eighth year of the copyright P applied for and registered the renewal copyright in Graff's name. P also assigned to itself Graff's interest in the renewal. Eleven days later, Graff himself applied for and registered the renewal copyright in his own name; and on October 24, 1939, he assigned his renewal interest to another music publishing firm, D. Both Graff and D knew of the prior registration of the renewal by P and the latter's assignment to itself. D published and sold copies of 'When Irish Eyes Are Smiling,' representing to the trade that it owned the renewal rights in the song. P brought this suit to enjoin these activities. The District Court granted a preliminary injunction to P. The Court of Appeals for the Second Circuit affirmed. The Supreme Court granted certiorari.