FEW financial scandals have had more implications than the one tied to the London Interbank Offered Rate (LIBOR). A number used in the pricing of at least $300 trillion in securities was found to have been manipulated for years. Three banks have paid serious fines: RBS, UBS and Barclays. Careers have been shattered. Yet an unresolved question remains: was there a violation of law?

The answer is, largely, no, according to a 161-page opinion released on March 29th by Naomi Reice Buchwald, a federal judge in the southern district of New York. Most of the American civil litigation has been consolidated in her court and the sheer scope of the opinion is an implicit acknowledgment that the conclusions will be carefully reviewed. In part, this is because it encompasses so much: the structure of an international component of domestic financial markets, the limits of American law and the time constraints for filing claims. But a larger factor is simply the size of the potential claims, which are substantial.

Ms Buchwald’s most important ruling was to dismiss claims that banks conspired to manipulate rates, violating competition law. That may seem surprising. Traders acknowledge submitting false prices; they had financial incentives to do so. But nothing is entirely obvious when it comes to LIBOR because of the odd way it is set.

During the period between August 2007 and May 2010 covered in the litigation, 16 banks participated in a panel under the auspices of the British Bankers’ Association, providing daily estimates of what their own borrowing costs would be, even if they never borrowed. The highest and lowest sets of prices were thrown out; the rest averaged. This was not, Ms Buchwald wrote, a competitive market—the price was not a bid and nothing was bought. It was a co-operative process and thus competition laws did not apply.

With that decision, Ms Buchwald in effect dismissed claims brought by three of the four core groups of plaintiffs: holders of LIBOR-linked bonds, of mutual funds and of over-the-counter securities. That left only those who traded LIBOR-linked contracts on the Chicago Mercantile Exchange as the focal point for litigation. Retaining even these claims was no sure thing. Ms Buchwald rejected the notion that LIBOR manipulation occurring in London was covered by American law. But she accepted that LIBOR alleged to have been used to manipulate prices of contracts traded in Chicago was. This is the second big case to touch on the issue of how American law affects financial products traded elsewhere, and more are coming.

Still, even these plaintiffs did not fare particularly well, as Ms Buchwald dismissed many claims for having been filed beyond the two-year limit from when news reports of LIBOR problems first appeared. “We recognise”, she wrote, “that it might be unexpected that we are dismissing a substantial portion of plaintiffs’ claims, given that several of the defendants have already paid penalties to government regulatory agencies reaching into the billions of dollars.”

The reason, she says, is that public and private enforcement can differ, with the government actions tied to “broad public interests” such as the integrity of the market and competition, and private actions hinging on whether a particular plaintiff deserves compensation. Her exoneration of the defendants rests in large part on the premise that the real problem was not in fake data but in a fake market. Maybe in the next go-round plaintiffs should take a crack at whoever promoted such a market in the first place.