Copyright law requires that copies deposited in the Copyright Office be of the “best edition” of the work. The best edition of the work is the edition the Library of Congress determines is the most suitable for its purpose.
When multiple editions of a work have been published, the one of the highest quality is generally considered to be the best edition. When judging quality, The Library of Congress adheres to specific criteria. A criterion by criterion comparison of the two editions is made, and the first edition that fails to satisfy a certain criterion is deemed of inferior quality and will not be the acceptable deposit.
Potential depositors may request authorization to deposit copies other than the best edition of a given work by requesting “special relief” from the deposit requirements. All requests for special relief should be in writing and should state the reason why the applicant cannot send the best edition and what the applicant wishes to submit instead.