Justice Department, Federal Reserve also can appeal the Wednesday ruling that threw out the 21-cent cap set by Durbin Amendment.
Two instead of four unaffiliated payment networks could be required as result of federal judge's ruling.
Trades also indicate possible appeal after federal court throws out Fed's 21-cent cap.
Federal judge throws out Durbin Amendment's 21-cent cap in emphatic ruling.
The European Commission has proposed capping debit and credit card interchange at 0.2% and 0.3% respectively.
A new survey of debit issuers representing about 45% of U.S. debit traffic suggests the debit industry is living on less interchange but is also experiencing less fraud.
Merchant Payment Coalition says study claiming interchange impact did not include enough data.
Survey covering almost half of U.S. debit traffic finds two-cent decrease reported in interchange rates from exempt issuers.
This year saw a regulation capping the interchange card issuers were able to earn on a debit card transaction come into effect for the first time in history.
The issue of revenue that banks and credit unions make from transactions on their debit cards moved from the obscure corners of the financial services industry into the national spotlight last week as the Federal Reserve's debit interchange cap came into effect.