A European Commission competition ruling in 2007 prohibiting multilateral interchange fees by MasterCard was upheld by the General Court of the Court of Justice of the European Union on May 24, 2012.
For the text of the ruling, see European Court of Justice judgment T-111/08 MasterCard and Others v Commission (Competition).
The
 European Commission ruling had a significant effect on credit card 
charges at the time, as MasterCard halved its charges in 2009 to avoid 
penalties.
Visa Europe reduced debit card charges in 2010, but EU 
Competition Commissioner Joaquin Almunia has said that fees on card transactions are too high and that formal charges against Visa Europe are being readied.
Crossposted at LawPundit.