The European Commission is looking into how mobile Internet providers are managing data across their networks, opening up a new storm of debate around the idea of net neutrality. The review is in part gearing up for a new European telecommunications law, which takes effect May 25.

Ars Technica’s Nate Anderson writes that there’s a reason for interested parties to be concerned about the issue,

As today’s Commission report noted, throttling of file-sharing and video streaming traffic has been reported in France, Greece, Hungary, Lithuania, Poland, and the United Kingdom. Blocking or charging extra fees for VoIP has been reported on mobile operators in Austria, Germany, Italy, the Netherlands, Portugal, and Romania.

It’s not clear that the new law will give sufficient guidance. PCWorld’s Jennifer Baker writes,

There is no set definition of “net neutrality” in the European Union, but it will be a legal requirement when the new Telecoms Package comes into force on May 25. This new law, which sets out rules on transparency, quality of service and the ability to switch operator, must be applied in a way “that ensures open and neutral Internet principles are respected in practice.” However, it does not specify how member states may achieve this, leading to confusion in some countries about how to adopt the law.

Some companies and organizations are complaining that there are already big problems with how European carriers treat data traveling on the mobile Internet, writes the New York Times,

Advocates of network neutrality criticized the inquiry as insufficient, saying that the fact-finding mission was superfluous and ignored obvious, continuing problems with the mobile Internet. Operators, for example, do not connect Skype calls over their networks because the Internet calling company’s services would siphon revenue from their own businesses.

“The European Union appears to be alone in the developed world in tolerating on such a wide scale these types of arbitrary restrictions on Internet use,” said Jean-Jacques Sahel, the director of government and regulatory affairs for Skype in London. “It has to cease and we look to European authorities to unambiguously protect consumers.”

Though the European Union is well known for the hard line it took with Microsoft in its antitrust investigation, it’s not yet clear how the Commission will position itself in this case. In a press conference, Neelie Kroes, European vice president for the digital agenda, toed a careful line between the interests of the operators and those of their opponents, saying,

Today’s report shows a general consensus that traffic management can be useful. For example, it is important to keep video calls running smoothly even if that means an email is delayed by a few seconds. Consumers have the right to choose services, and operators have the right to deliver services, that can meet these expectations. I do not like the blocking or degrading of certain services. But if there is such blocking or degradation, then the customer needs to be clearly informed in advance so that they can make an informed choice about the operator that gives them what they want. It is clearly not OK to block or degrade lawful services by stealth, without informing the customer.