What began as a rallying cry for free speech has turned into a legal migraine for three young Webmasters who publicized decoded material belonging to an Internet firm that filters smut from children's computers.

The men, all in their early 20s, were ordered by a judge to take down the information or face charges of copyright violations--the first time such a law has been successfully applied in the hotly contested filtering debate.

Today the alleged offenders got the relief they were looking for when veteran civil liberties lawyer Chris Hansen offered to take on the fight against the filtering firm, Cyber Patrol.

"Filtering is a huge public controversy, and it's not clear that the court has the authority on the issue," said Hansen, a longtime attorney with the American Civil Liberties Union. A hearing on the matter is scheduled for Monday in U.S. District Court in Boston.

Filtering software is designed to shield children from illicit material circulating on the Web. But opponents such as Hansen and his clients say the filters also tend to block sites that aren't pornographic or offensive.

To demonstrate their position, many tech-savvy critics have figured out how to circumvent blocking software and expose a company's secret list of barred Web sites.

But Cyber Patrol, and many other firms like it, argues that the lists are trade secrets and that gaining access to the material by cracking software codes is a copyright violation.

This court battle could settle the question of whether code cracking, also called "reverse engineering," is unlawful. The Digital Millennium Copyright Act put some of these issues to rest when it passed in 1998. The act imposes safeguards for software, music and written works on the Net and outlaws technologies that can crack copyright-protection devices.

But the act also makes allowances for research, which is still being tested in the courts.

Until now, the major decisions surrounding filtering have focused on free speech and access to the Internet from government-subsidized institutions such as libraries and schools.

The distribution of decoded information has annoyed filtering companies, but none has taken the legal steps that Cyber Patrol has pursued.

Trouble for Bennett Haselton, operator of Peacefire.org, and the other two defendants began about two weeks ago when they posted on their Web sites a program that allowed Cyber Patrol subscribers to bypass the company's filter.

They got the program from two other men, Matthew Skala of Canada and Eddy Jansson of Sweden.

Cyber Patrol promptly obtained a restraining order from a federal judge in Boston, forcing Skala and Jansson, as well as all other Web operators who had distributed the program, to take down the decoded information from their sites. The company also moved quickly to block the sites from their clients.

"The way these guys obtained the source code, we consider it to be a slam-dunk copyright infringement case," said Sydney Rubin, spokeswoman for Cyber Patrol. "It was our obligation to protect our clients."

Rubin noted that the original code crackers then copyrighted protections for their findings.

"These two hackers cavalierly broke copyright laws to serve their own self-aggrandizing, then sought protection under the same law to safeguard their own work," she said.

Defendant Haselton has built a career out of publishing ways to circumvent filtering software. Just two weeks ago, he posted links to a list of blocked sites belonging to Symantec subsidiary iGear. A company attorney warned him that the move poached iGear's intellectual property.

Despite his brushes with the law, Haselton remains confident he will prevail in court.

"I think in the long run it will be established that this is legal," he said. "We don't copy the program, we just figure out how it works."