Matthew Keys, the 26-year-old deputy social media editor at Reuters charged with assisting computer hackers, has emerged as the latest lightning rod in the continuing battle between proponents of Internet freedom and the Justice Department.

A federal indictment of Mr. Keys filed in California on Thursday met an online cacophony of protests against the 1984 computer crime law under which he was charged, the Computer Fraud and Abuse Act.

The indictment says that Mr. Keys, who previously worked as a Web producer at KTXL Fox 40, a Sacramento-based television station that, like The Los Angeles Times, is owned by the Tribune Company, provided a user name and password to hackers associated with the group Anonymous. Those hackers then changed a headline on a Times online article from “Pressure Builds in House to Pass Tax-Cut Package” to “Pressure Builds in House to Elect CHIPPY 1337,” a reference to another hacking group.

Each of the three charges against Mr. Keys could result in fines of as much as $250,000, with possible prison terms of as many as five years in one count and as many as 10 in the other two. The Tribune Company spent more than $5,000 to update its systems in response to the attack, the indictment says.