More cheer for US firms and boutiques as Libor row stokes contentious banking market, reports Friederike Heine

"Law firms are having a field day on Libor," comments a London litigation head at a US law firm, summing up the private mood in the week following Barclays' admission to manipulating global interest rates.

Even for banking advisers grown used to continually expanding levels of contentious and regulatory work from institutional clients, the furore in the wake of the bank's announcement that it had agreed a $450m (£290m) settlement looks to kick things up to a whole new level, legally speaking.

So fundamental is the alleged rigging of Libor and Euribor – key benchmark rates for inter-bank lending and the setting of trillions of pounds worth of contracts – that many of the world's largest banks are expected to be embroiled in ensuing regulatory sanctions, litigation and even criminal inquiries.

"These mandates are enormously lucrative for law firms for a number of reasons," says one London banking partner. "Billions of dollars in financial instruments are Libor-indexed, so the damages could be mind-boggling, and the litigation has the potential to last for years. Secondly, the mandates are multi-disciplinary, which means that firms can make a killing by cross-selling to other departments."

If such contentious work is lucrative and pleasantly high-margin to corporate law firms wrestling with suppressed deal activity, it is particularly well-pitched for American advisers, given the prospects of US proceedings or claims from investors.

Sullivan & Cromwell has taken the lead for Barclays regarding the US Commodity Futures Trading Commission (CFTC) and the Department of Justice (DoJ), which initially brought the charges against the bank.

New York-based litigation partners Steven Peikin, David Braff and Jeffrey Scott provided counsel on the settlement, with $200m (£130m) of the penalty going to resolve the CFTC's civil case – the agency's largest-ever fine – and $160m (£100m) to settle the DoJ action. The £59.5m paid to the Financial Services Authority (FSA) as part of Barclays' settlement is, likewise, the largest penalty the FSA has ever levied.

Gibson Dunn & Crutcher, meanwhile, has been acting for UBS on a number of pending class actions in the US, as well as providing defence counsel in US regulatory proceedings. Simpson Thacher & Bartlett is advising longstanding client JP Morgan, while Paul Weiss Rifkind Wharton & Garrison – generally regarded as Wall Street's top litigation shop – is acting for Deutsche Bank.

Davis Polk & Wardwell is acting for Bank of America Merrill Lynch, while Shearman & Sterling has won a role for Credit Suisse. Hogan Lovells is advising legacy HBOS, now part of the Lloyds Banking Group and a longstanding client on both sides of the Atlantic.

One partner at a US firm comments: "The US regulators have been quicker off the mark and more aggressive, which means that most banks have turned to US firms in the first instance. In addition, the US market lends itself to litigation and class actions, which means that leading banks will be quicker to appoint counsel."

Overall, the Libor saga will certainly be yet another incentive for major law firms to continue investment in strategic practice lines with a distinctive US flavour such as corporate investigations and white collar crime.

But if the Libor fallout plays to the strength of US-based advisers, major City firms will be intent on securing work in such high-stake scenarios.

Already quick off the mark is Clifford Chance (CC) which – in an unusual move – took roles for both Barclays and the Royal Bank of Scotland (RBS), with London-based teams separated by a Chinese wall.

Norton Rose has also secured a high-profile mandate to advise Barclays' former chief executive Bob Diamond.

Further expanding the scope for UK advisers is the confirmation that a Parliamentary inquiry, which will take evidence on oath and be assisted by counsel, will investigate the matter.

And while the FSA has limited scope to pursue criminal investigations in relation to Libor, the Serious Fraud Office last week confirmed that it is investigating the matter, though lawyers remain somewhat sceptical of what the resource-starved agency can achieve.

Given this scope, the firms that have won instructions in relation to Libor manipulation are fielding multi-disciplinary teams, with partners at two magic circle firms confirming that they are forming teams of litigation, regulatory, banking and white-collar defence partners to service the banks.

A key factor that will define how Libor plays out for legal advisers will be if the matter generates substantial bank v. bank disputes, as some believe. For this reason, there has been some surprise at CC's decision to take on a dual role on the Libor case.

One firm that had considered pitching to represent RBS says the bank specified a willingness to litigate against other banks, a stipulation that could potentially play havoc in the City market in which law firms strenuously avoid suing banks.

As such, Libor-related work also looks to be another shot in the arm for the growing band of litigation-focused boutiques that are free to pursue major banks. While such firms were in short supply in London until recently, the rapid progress made by Quinn Emanuel Urquhart & Sullivan in recent years and growth of practices such as Stewarts Law and Enyo Law is changing that dynamic.

Stewarts Law head of litigation Clive Zietman comments: "The few law firms that are not conflicted from acting against banks are actively engaging with clients in relation to Libor issues. What is certain is that this saga has already been extremely damaging to the banks from a reputational perspective. The civil, criminal and regulatory implications are huge. But until more facts emerge, it is hard to see exactly how this will play out."

However the Libor scandal develops, its ultimate significance could be in delivering another body blow to a banking industry already under huge pressure to reform and restructure under a host of international measures such as Basel III and the Vickers reforms in the UK.

These forces suggest a move towards a somewhat smaller and more much heavily regulated finance industry that will remain a major source of income for law firms. However, the pattern of that income is on course to gradually but inexorably shift from (sometimes commoditised) transactional instructions towards increasingly high-stakes contentious work.

No matter how much the banking industry resists such outside pressure to curb its excesses, nearly five years on since the credit crunch, there is little indication that the global economy and sustained austerity in Western economies will let it off the hook.

Such a profound shift in finance would have considerable implications for law firms – though generally more lucrative ones than for their clients.