THE charges were bound to generate big headlines for a little-known regulator. Barclays, a British bank already tainted by its role in fixing LIBOR, a vital interest rate, was accused on July 17th of manipulating electricity prices in California and other states, and slapped with a $453m fine by America’s Federal Energy Regulatory Commission (FERC). Yet the bank soon deviated from the usual script. Instead of accepting its punishment, Barclays contested the ruling, saying it was “unsupportable” and that its trading was legitimate.

The bank’s belligerence is atypical: financial firms try to avoid open conflict with their regulators. But many European bankers will be privately cheering Barclays on. There is a widespread belief that when it comes to foreign banks, American justice is more one-eyed than blind.

The evidence for this belief is circumstantial. American institutions are among the world’s biggest, yet the list of banks that have agreed to pay huge fines to regulators in the United States is largely foreign. The three banks that have already agreed settlements for LIBOR manipulation are European; so are the three thought likely to strike deals later this year. “It hasn’t escaped anyone’s notice that the investment banks that have been targeted are not American,” says one figure in London.

An analysis by Bloomberg News of the LIBOR-related charges filed in America and Britain against Tom Hayes, a former trader at Citigroup and UBS, reveals something even more curious. In Britain Mr Hayes was charged with misconduct during a period when he worked at Citigroup and at UBS. In America the charges cover only the period when he worked for the Swiss bank and mention no other firms.

Foreign banks also seem to have been dealt with more harshly than their American counterparts on other offences such as money-laundering or sanctions-busting. HSBC, a British bank, last year agreed to pay a $1.9 billion fine for failing to prevent money-laundering by drug cartels. At about the same time Standard Chartered, another British bank, agreed to pay $667m for facilitating transactions with Iran (after briefly threatening to fight the charges). The fines dwarf those imposed on American banks for similar infractions. In 2010 Wachovia, a subsidiary of Wells Fargo, agreed to pay a fine of $160m for laundering money for Mexican drug cartels.

Jeffrey Lehtman, an attorney in Washington, DC, with Allen & Overy, a law firm, thinks that business mix may explain the apparent differences in fines. International banks with large networks are most at risk of big penalties; Europe has more of these lenders than America does. Apparent differences may also be down to timing. Several American banks are understood to be in talks about LIBOR settlements; JPMorgan Chase is reportedly in settlement talks with the FERC. That may balance the scales. Moreover, the severity of sanctions has jumped recently. Similar infractions may attract larger penalties today than they did before. Even so, unless American banks are genuinely squeaky clean or some big prosecutions are in the works, claims of uneven treatment will persist.