BMG Rights Management and Round Hill Music want Cox to reveal the identities of hundreds of subscribers whose accounts were frequently used to pirate music. The request is part of an ongoing lawsuit where the ISP is accused of failing to disconnect repeat copyright infringers.

In the United States most large Internet providers forward DMCA notices to subscribers who’re accused of downloading copyrighted material.

Cox Communications is one of the ISPs that does this. In addition, the ISP also implemented a strict set of rules of its own accord to ensure that its customers understand the severity of the allegations.

According to some copyright holders, however, Cox’s efforts are falling short. Last year BMG Rights Management and Round Hill Music sued the ISP because it fails to terminate the accounts of repeat infringers.

The companies, which control the publishing rights to songs by Katy Perry, The Beatles and David Bowie among others, claimed that Cox has given up its DMCA safe harbor protections due to this inaction.

The case revolves around the “repeat infringer” clause of the DMCA, which prescribes that Internet providers must terminate the accounts of persistent pirates. Both parties are currently conducting discovery.

In order to make their case the copyright holders have sent a long list of demands to Cox, but court records show the ISP is reserved in the information it’s willing to hand over.

The company refused, for example, to reveal the identities of roughly 150,000 subscribers who allegedly downloaded infringing works from BMG and Round Hill Music. According to the ISP, the Cable Privacy Act prevents the company from disclosing this information.

The music groups, however, aren’t taking no for an answer and are now asking the court to compel Cox to hand over their personal details. According to them, this information is crucial to proof the direct infringement claims.

The copyright holders are willing to accept a more limited number of accounts to begin with. In a motion to compel, they ask for the personal details of 500 account holders whose accounts were repeatedly used to share pirated material.

“In an effort to narrow the dispute, Copyright Holders only request the identity of and contact information associated with 500 of what appear to be the most egregious infringers,” they write.

“Specifically, Copyright Holders seek the identity of subscribers associated with 250 IP addresses that have infringed the copyrights at issue since the complaint was filed in this case, and the identity of subscribers associated with 250 IP addresses that have infringed in the six months prior to the Complaint being filed,” the companies add.

While the current request is limited to 500 IP-addresses, the music groups reserve the right to request more at a later stage and ask the court to grant permission to do so.

“Copyright Holders also request that the Court issue an open Order requiring Cox to produce the contact information for additional direct infringers of the copyrights at issue in this case, if the need arises,” they write.

There is a hearing scheduled for later this week when the copyright holders will further detail their request, if needed. Cox has yet to respond but it’s unlikely that the company will hand to hand over the requested information without putting up a fight.