Boston University students have won what one lawyer hailed as a "David and Goliath" victory after challenging one of the recording industry's most aggressive tactics: lawsuits targeting people who illegally download music.

US District Judge Nancy Gertner ruled this week that the university cannot turn over the names of students to several major record companies that sued for the information until she can do a more in-depth review. The ruling, for the moment, quashes the companies' efforts to hold the students liable for copyright infringement, which could have resulted in thousands of dollars in fines. Lawyers who supported the students said the decision would make it harder for record companies to win some 20,000 similar cases they have brought nationwide.

"This is definitely a step in the right direction," said Raymond Sayeg, a Boston lawyer who represented one of the four BU students who challenged the record companies. "The court has recognized the right of privacy of the students."

Sayeg compared the victory to that of David over the giant Goliath in the Bible.

"You have on the one hand maybe 30 to 40 of the largest record companies in the country, and they're singling out students at institutions of higher education. So it's a real mismatch."

The decision adds a layer of protection for the thousands of people, many of them students, sued by the Recording Industry Association of America, according to Fred von Lohmann, staff attorney at the San Francisco-based Electronic Frontier Foundation, which filed a brief in support of the BU students.

"It does not mean the end of the issue," von Lohmann said. "It is not going to slow down the RIAA litigation machine, and they'll continue to sue hundreds a month all over the country. But the judge said they have more work to do if they want to prove these cases."

Undaunted, the record company organization said it would press ahead with the lawsuit.

"It's important to note that the decision is not final," said Jonathan Lamy, the organization's senior vice president of communications. "The court has put forth a specific process to address its concerns before the relevant information is transferred to us. We're confident that the court will ultimately allow us to obtain the [names], as have courts across the country in similar cases."

File-sharing exploded in popularity in the late 1990s with the advent of Napster, which allowed people to swap songs from one computer to another. A series of lawsuits by record companies killed the service in 2001 but spawned a host of imitators, such as Kazaa and Limewire. In 2003 the recording industry began to attack those services - by going after their users. The industry filed 35,000 lawsuits to stop illegal music downloading through the programs, which it blamed for billions of dollars in lost sales.