The judge dismissed charges brought by Princeton University professor Edward Felten, who said legal threats stopped him from publishing a paper outlining the weaknesses in the industry's technologies for protecting digital music.
Felten hadthe Recording Industry Association of America, which represents major music labels, because the association sent him a letter threatening legal action if he published his research.
"The court has put the scientists in a position where they have to beg Hollywood to publish their research," said Robin Gross, staff attorney for intellectual property at the Electronic Frontier Foundation, which represented Felten. "It puts the researchers at risk."
Both the Justice Department and the RIAA asked the court to dismiss the case. Judge Garrett Brown of the Federal District Court in Trenton, N.J., agreed Wednesday.
The DMCA, passed in 1998, prohibits the circumvention of copy protection and the distribution of devices that can be used to bypass copyrights--even if their users don't do anything illegal once they've broken the security. Software makers, Hollywood and the music industry make up the core proponents of the law.
The judge's ruling has not yet been made available.
However, in its motion filed on behalf of the DMCA, the Justice Department said that Felten's concern over being prosecuted under the law has not stopped him from publishing.
"Whatever concerns (Felten and others) actually harbor, it appears that they have not forgone a single publication of any material as a result of those concerns, and they do not allege that they will actually forgo any conduct in the future," the DOJ wrote in its motion. "In short, plaintiffs' speech has not been chilled."
In a statement issued Wednesday, Cary Sherman, senior executive vice president and general counsel for the RIAA, praised the decision.
"We are happy that the court recognized what we have been saying all along: There is no dispute here," he said. "As we have said time and again, professor Felten is free to publish his findings."
The EFF's Gross says the organization will "most likely" appeal the case.