Universal Music Group and Sony Music Entertainment have urged a federal court to reject Suno’s bid to keep secret the total number of audio files it used to train its AI music model.
In a memorandum of law filed on Friday (June 5) in the US District Court for the District of Massachusetts, the labels argued that Suno cannot overcome a “strong presumption of public access” to court pleadings. The filing, obtained by MBW, can be read in full here.
At issue is a single figure the filing calls the “Model Training Figure.”
It represents the total number of audio files the labels allege Suno used to train its generative AI model.
UMG and Sony had initially redacted the number from their own court papers “in an abundance of caution,” but reserved the right to contest sealing.
The fight over the figure is one of two fronts on which the labels and Suno are now battling in a copyright case that has been running for nearly two years.
The labels asked the court on May 21 to add 61,026 recordings to the suit, after using audio-fingerprinting service Audible Magic to identify their works inside Suno’s training data.
Suno opposed that motion on Thursday (June 4), arguing the labels had “unduly delayed” and that expanding the case would deny it a timely ruling on its fair use defense.
Separately, Suno moved to keep the training-data figure under seal, citing the risk of competitive harm.
In their opposition, UMG and Sony argued that the figure appears in filings tied to their proposed amended complaint, where “the presumption of public access is at its strongest.”
The number is relevant to Suno’s fair use defense, the labels argued, because it “speaks directly to the nature and extent of Suno’s copying.”
The memorandum noted that Suno had asserted that disclosure “could cause Suno serious commercial harm.”
UMG and Sony called that claim speculative: “Such speculation is insufficient as a matter of law to justify impoundment.”
“Stripped of its conclusory assertions of competitive harm, there is no cognizable reason to shield from public view how many sound recordings—including Plaintiffs’ recordings—Suno copied to build its service.”
memorandum of law filed by UMG and SOny on June 5
The filing said Suno had argued that competitors “could” use the figure to “replicate and benchmark” their own systems, “infer” aspects of its training, and “potentially optimize their models to unfairly compete with Suno.”
None of those justifications “withstand scrutiny,” the labels told the court, pointing to a declaration from Suno’s chief technology officer.
The declaration from Georg Kucsko, the filing said, “asserts only that Suno treats its training data as confidential as a general matter.”
Any harm would be limited, the labels argued, because the scale of Suno’s copying is already a matter of public record.
In its answer to the complaint, Suno admitted that building its service “required showing the program tens of millions of instances of different kinds of recordings.”
“Having publicly acknowledged copying of that magnitude, Suno cannot credibly claim that disclosing a slightly more precise count of the audio files that its AI model trained on would reveal anything competitively sensitive,” the filing reads.
The labels also urged the court to reject Suno’s request to redact a second figure.
That number reflects the recordings the labels identified in Suno’s training data as ones they had provided to Audible Magic, and is a subset of the larger total.
The labels argued Suno had waived any objection to disclosing it, because its motion made no argument for sealing that figure.
“Contentions that are not developed or supported in a party’s submissions are deemed waived,” the filing states, citing prior rulings in the District of Massachusetts.
The labels concluded that there was “no cognizable reason to shield from public view how many sound recordings — including Plaintiffs’ recordings — Suno copied to build its service.”
The case was originally filed in June 2024 by the RIAA on behalf of all three major music companies, with Judge F. Dennis Saylor IV presiding. The original complaint asserted 560 works.
Warner Music Group, a former co-plaintiff, settled with Suno in November 2025 and entered a licensing partnership, leaving UMG and Sony as the remaining plaintiffs.
The filings landed days after Suno raised over $400 million in a round that valued the company at $5.4 billion.
Fact discovery in the Suno case is scheduled to close on June 26, though the parties have discussed pushing the deadline into August.
Rival AI music company Udio was sued by the same labels in June 2024.
It is facing a similar dispute over the size of its training data in a separate case playing out in the US District Court for the Southern District of New York, in which Sony Music Entertainment is the sole plaintiff.Music Business Worldwide
