The fear of a cyberspy watching a Web surfer’s every move is leading to litigation in the untested legal realm of Internet privacy, and a suit filed recently in Dallas could help shape the issue in Texas. A suit filed Feb. 9 in Dallas state district court against Yahoo! Inc. and broadcast.com inc. seeks class-action status for some 50 million subscribers or users of those Web sites and contends they’re being illegally monitored.

The suit alleges that the companies’ use of cookies, or little text files written into a personal computer’s hard drive to identify a computer user, violates Texas’ anti-stalking law.