Europe's top court Thursday ruled that EU nations have the right to set limitations on noise pollution from aircraft roaring over built-up areas.

After a long-running dispute between the city of Brussels and a cargo airline, the European Court of Justice said EU states "can, theoretically, establish maximum noise levels, as measured on the ground, to be complied with by airlines overflying areas located near an airport."

The court stepped in after European Air Transport (EAT), a unit of the DHL group, asked for the reversal of a 2007 fine by Brussels authorities after one of its planes exceeded maximum evening noise levels over the city.

The company, which was fined 56,113 euros (some $76,000), argued the Belgian measure violated EU rules because it measured noise levels on the ground, not from the aircraft, and that the penalty amounted to an operating restriction.

But the court disagreed, defining an operation restriction as "a prohibition, absolute or temporary, that prevents the access of an aeroplane to an EU airport."

"Consequently, environmental legislation, such as that at issue in the present case ... does not itself constitute an operating restriction as long as it does not prohibit access to the airport in question."

But the court qualified the decision, saying that should environmental limits be "so restrictive as very clearly to force aircraft operators to forgo business," then such legislation would amount to a restriction on operations.

The court, which interprets law but does not decide on disputes, sent the case back to the Belgian courts to decide whether the noise levels set by the Brussels authorities were acceptable or not.