Public-Domain Verification Process

1. Policy: United States public domain only

Attacca makes a score available only where the specific file is recorded as public domain in the United States. Our catalog is drawn from a large public-domain archive that publishes, for each file it has reviewed, a copyright status for the particular edition, with a separate field for the United States. Attacca applies that published United States status file by file, together with stricter exclusions of its own, described below. Attacca does not itself search Copyright Office registration or renewal records. A file that may be public domain in another jurisdiction but not the United States is not made available. This is deliberate conservatism. Attacca operates from the United States, and a single strict standard is simpler to verify, to audit, and to defend than a per-jurisdiction model.

2. Verification pipeline

Files are checked at several stages from ingestion to delivery. The source archive's published United States status is the core datum; the stages below apply that same datum repeatedly, together with Attacca's own stricter exclusions, so that a file that fails at any stage is not served. They are layers of one check, not independent reviews of the law. When a gate gap or a mis-admitted file is identified, the file is withheld promptly and the correction is recorded in a dated withhold record.

• Source status. Each file in the source archive carries a per-jurisdiction copyright status tag, set by the archive for that specific edition. Attacca relies on the United States field of that tag and treats it as a necessary condition: it can exclude a file the tag would allow, but never admits a file the tag does not.
• Gate 1, ingestion scope. Our extraction step reads the per-file tag and places a file on the download list only where that tag indicates United States public domain.
• Gate 2, downloader. The downloader repeats the same check and does not store a file that is absent from that list.
• Gate 3, catalog build. A file enters the catalog only if its own United States status still holds and it passes Attacca's exclusions: we do not list a file the source marks only as “probably” public domain, a file whose recorded license label names a Creative Commons license (other than a CC0 public domain dedication) or a performance restriction, or a file on our block list. Since September 30, 2026, a file that was not in the catalog on that date is admitted only if its United States field is a plain public-domain mark (or a public-domain year already reached) and the source's data dates the work's first publication to 1930 or earlier, or, in a small number of listed cases, the file itself is confirmed to be an edition printed before 1931 or a reprint of one; any other new file is held back for review. The status is per file, not per work (see Section 4).
• Gate 4, serving. Score files are downloaded only through authenticated, metered download grants, never directly; page previews can be viewed without signing in, but only for files in the current catalog. On every download or preview request the server checks the block list, and every download request also checks the file's recorded public-domain status, so a file can be withheld within minutes; a withheld file cannot be downloaded or previewed, and it drops out of the catalog listings when the catalog is next rebuilt (a rebuild starts every six hours). Attacca applies one United States public-domain standard uniformly and does not use a visitor's location to vary the catalog or to restrict access. Public-domain status can differ outside the United States, and users there are responsible for compliance with their local copyright law, as set out in our Terms.

3. Audit log

Attacca keeps a per-file status record for every file available for download.

For each file, the record captures:

• the source's copyright status tag, as we captured it;
• the United States public-domain flag our pipeline derived from that tag, and the resulting decision, admitted or excluded;
• for most files (about 94 percent), the address of the source page and the time our pipeline read it; some older records do not hold those two fields.

Each file withheld since September 29, 2026 is also listed in a dated withhold record, and the block list takes precedence over the status record. A status record can be rewritten when a file is re-examined, so each night our pipeline records a cryptographic hash of the status records in a log in which every entry is chained to the one before it, and backs up the records and the log to cloud storage off the server. The log has no entries for September 4 to 29, 2026, when that nightly job did not complete. For any file in the catalog, Attacca can show the recorded status on which it is served, and a retained copy of the records for a night the log covers can be checked against that night's hash.

4. Edition-level copyright

Public-domain status is judged at the level of the individual digitized file, never the composer or the composition alone. The most common error in score reuse is to treat a public-domain work as though every edition of it were equally free. A modern critical or engraved edition of a public-domain composition can carry its own copyright. Because the United States status Attacca relies on is set for the specific edition in each file, an edition that is marked as protected is excluded on the strength of its own status, even when the underlying composition is unambiguously in the public domain.

5. Editorial originality and re-engraved editions

Attacca does not rely on its own view that urtext, scientific, or re-engraved editions of a public-domain composition lack copyrightable originality of their own. The source archive marks some files as public domain on the ground that the edition adds no original copyrightable material. Since September 29, 2026, Attacca has withheld such files wherever the same work has another edition with a plain public-domain status available. A small number of works (about 350) are for now available only in such an edition; those files remain available while we look for replacement files that the source marks as plainly public domain, and we will withhold each one once its work has such a replacement.

If you believe any specific edition has been incorrectly classified, please contact us through the DMCA process.

6. Foreign works and URAA restorations

A work or edition published before January 1, 1931 is in the public domain in the United States, whatever the date of the composer's death. Foreign works first published in 1931 or later need closer scrutiny. The Uruguay Round Agreements Act of 1994 (URAA) restored United States copyright on foreign works that remained under copyright in their source country on January 1, 1996. A work that appears to be US public domain by publication date alone may in fact be subject to URAA restoration, with US copyright extending until 95 years after first publication.

This is the area of United States public-domain analysis that most often produces close calls, and Attacca does not resolve those questions itself. On September 29, 2026 we withheld files of works that the source's data dates to a first publication after 1930 where the file's United States status depended on questions we had not resolved. Since September 30, 2026, a file not already in the catalog is admitted only if the source's data dates the work's first publication to 1930 or earlier; any other new file is held back for review. A small number of files already in the catalog, about 160, belong to works that the source's data dates to a first publication after 1930. The source marks each of those files public domain in the United States, so they remain available, and they are listed for further review. If you believe a specific work or edition is incorrectly available, please contact us through the DMCA process and we will act on it promptly.

7. Content sourced through institutional partnership

The catalog does not currently include scores obtained through an institutional partnership. If Attacca adds such scores, the partner institution's own public-domain determination will be the primary basis for inclusion. A library that digitizes only works it has itself determined to be in the public domain, under a documented and conservative standard, arrives pre-vetted. Attacca's gates and records will then serve as a documented confirming check rather than an independent re-adjudication, and every item will retain its source identifier as a provenance link back to the originating institution.

8. Legal posture

For the catalog, Attacca's position rests on substance rather than procedure: content is admitted only on a documented, good-faith determination that it is in the public domain in the United States, based on the source's published per-file status and our own exclusions, so that for any file Attacca can show the basis on which it was made available. The verification pipeline and the records exist to make that basis demonstrable, file by file. When a mislabeled or mis-admitted file is identified, whether by our own review or by a credible report, Attacca withholds it promptly, keeping its status record and listing it in a dated withhold record. Conservatism in what is admitted, documentation of every decision, and prompt correction are treated as the core of responsible operation.