Groups such as the and the hope that the settlement -- which has yet to be approved by the court -- will provide an opportunity to address privacy concerns and clearly spell out what Google will do, for example, if approached by a government agency and asked for a record of what a user has read.

"It gives us an opportunity to get them to commit in legal language, in a binding document that would be different than all the other products, which are sort of ad hoc," Schultz of the Samuelson Clinic said.

If the settlement agreement isn't modified by the court or the parties involved, however, the activists will have lost that opportunity. But they may be able to push for privacy protections via the U.S. Department of Justice, which has opened an inquiry into Google Book Search, or simply by putting public pressure on Google to respond to their concerns.

At present, the agreement is "absolutely silent on user privacy," said Angela Maycock, assistant director with the American Library Association's Office for Intellectual Freedom.

Google has made a lot of statements about privacy, she said, "but they're informal statements, and we need to make sure that those informal statements and assurances actually get codified into policy."