monopolies have come under threat from Web sites based in offshore locations like Gibraltar

highest court in the European Union ruled Wednesday that Germany’s efforts to protect state-run gambling monopolies violated E.U. laws. The ruling gives a boost to private betting companies that are eager to break into the lucrative German market.

Germany, like a number of other European countries, has been trying to keep sports betting, lotteries and some other kinds of gambling under the control of state-run operators, saying this protects consumers from fraud and addiction. But lately these monopolies have come under threat from Web sites based in offshore locations like Gibraltar and from hundreds of sports betting shops that have taken advantage of gray areas in the law to open their doors in cities across Germany.

The European Court of Justice in Luxembourg said Wednesday that Germany had undermined its consumer-protection argument by letting state-run operators engage in “intensive advertising campaigns” and by permitting a proliferation of automated gambling machines, which the court said were highly addictive.

“In such circumstances, the preventive objective of that monopoly can no longer be pursued, so that the monopoly ceases to be justifiable,” the court said.