Neelie Kroes, the European Union's antitrust commissioner, termed "totally unacceptable" U.S. criticism of an EU court's ruling against Microsoft. Besides creating diplomatic friction, the U.S. Justice Department's criticism of the decision, which upheld European antitrust sanctions against Microsoft, sparked a debate among U.S. lawyers over its propriety.

These lawyers and Kroes argued that the statement issued by Justice Department antitrust chief Thomas Barnett the same day as the EU ruling disrespects the European court.

"I think it's totally unacceptable that a representative of the U.S. administration criticizes an independent court of law outside its jurisdiction," Kroes told reporters in Brussels. "It's absolutely not done. The European Commission doesn't pass judgment on rulings by U.S. courts, and we expect the same degree of respect from U.S. authorities for rulings by EU courts."

If Microsoft and other parties involved in the case "aren't happy" with the ruling, they can appeal to the European Court of Justice, the EU's highest court, Kroes said. They have two months to file an appeal.

Justice Department spokeswoman Gina Talamona declined to comment.

Barnett had criticized the Monday ruling by the European Court of First Instance in Luxembourg, which backed the EU's 2004 decision that ordered Microsoft to disclose proprietary data and strip music and video software from a version of Windows.

The ruling harms consumers by "chilling innovation and discouraging competition," Barnett said.

Lawyers critical of Barnett's statement said it was made in a different context from earlier Bush administration criticism of antitrust action against Microsoft by European and Korean authorities.

"Ratcheting it up as Barnett did by specifically criticizing a court decision may have touched more of a sensitive nerve," said Andrew Gavil, who teaches antitrust at Howard University's law school in Washington, D.C. Such comments "undermine the ability to develop a responsible global system of rule of law," he said.

Barnett's statement "potentially devalues the input from American policymakers" seeking to harmonize U.S. and European antitrust standards, said San Francisco lawyer Daniel Wall, who represents some of Microsoft's competitors.

This isn't the first trans-Atlantic war of words over antitrust policy.

In 2001, former U.S. Treasury Secretary Paul O'Neill called the EU's veto of General Electric's proposed $47 billion merger with Honeywell International "off the wall." The U.S. also criticized an EU probe of IBM in the early 1980s.