One of the oldest contested file-sharing cases has come to an abrupt and unexpected end. In a motion filed last month, but only uncovered today by Ray Beckerman, the RIAA has dismissed a two-year-old lawsuit filed against Joan Cassin. The dismissal is without prejudice, which means the RIAA could sue Cassin once again, but Cassin's attorney would likely argue that the label's recent dismissal is a final adjudication on the merits; more on that below.

Cassin was sued in April 2006 for copyright infringement. The boilerplate complaint used by the RIAA at the time is light on the details, but the exhibits attached to the filing show that MediaSentry detected a user with the handle omc@KaZaA sharing 406 files on KaZaA, including tracks from Madonna, Bob Seger, Dixie Chicks, and Sade.

Instead of filing an answer, Cassin's attorney (who works at the same law firm as Beckerman) filed a motion to dismiss in early 2007. One of the issues raised in the motion was the now-well-known argument that merely making a file available over a P2P network constitutes distribution. Indeed, Warner v. Cassin looked as though it would be one of the first cases where the issue would be argued in court.

Instead, the oral arguments never took place, and in the months since, a handful of rulings have come down on the making-available argument. The first, in Elektra v. Barker, largely went the RIAA's way, as a judge said that offering copyright music on a P2P network infringed on the label's publication right spelled out in the Copyright Act.

Subsequent rulings, however, have gone the other way. In early April, a federal judge in Massachusetts quashed an RIAA subpoena seeking the identities of Boston University students suspected of copyright infringement. "Merely because the defendant has 'completed all the steps necessary for distribution' does not necessarily mean that a distribution has actually occurred," wrote Judge Nancy Gertner in her ruling. "As noted above, merely exposing music files to the Internet is not copyright infringement."

And in Atlantic v. Howell, a case where the defendants are representing themselves, a judge denied the label's motion for summary judgment, ruling that the label had not proven that any actual distribution had taken place.

Beckerman told Ars that he suspects that the RIAA may have been concerned about the impact of those recent rulings on Warner v. Cassin. "They were afraid of [Warner v. Cassin] Judge Robinson deciding the case, because his would be the most well-informed decision so far."

The RIAA rarely reveals the particulars of why it dismisses individual cases, and has not yet given Ars its perspective on the case. Historically, the group has walked away from cases where there's significant doubt that it would prevail, and it may have concluded that this lawsuit fell into that category. Since the case was dismissed without prejudice, the RIAA could refile it, but Beckerman believes that under federal court rules, which count the second dismissal of the same case as an "adjudication on the merits," Cassin should be considered the prevailing party. Under his reasoning, the first case was the filing and dismissal of a John Doe lawsuit for the sole purposes of obtaining Cassin's identity from the ISP.