Google Inc.'s (GOOG) mysterious methods for ranking Web sites came under attack Friday in a lawsuit accusing the online search engine leader of ruining scores of Internet businesses that have been wrongfully banished from its index.

The civil complaint, filed in U.S. District Court in San Jose by KinderStart.com, seeks to be certified as a class action representing the owners of all Web sites blacklisted by Google's Internet-leading search engine since January 2001.

KinderStart, a Norwalk, Calif.-based Web site devoted to information about children, says it was dropped from Google's index a year ago without warning.

"The world is becoming increasingly 'Googlized,'" said Gregory Yu, a lawyer for KinderStart. "For most people, that has been a good thing, but not for everyone."

A Google spokesman said the company hadn't seen the suit and had no immediate comment.

KinderStart alleges Google has engaged in anticompetitive behavior and misled the public by positioning its search engine as an objective source for finding Internet content. The suit seeks unspecified financial damages and a court order that would require Google to change its ways.

The case aims at Google's heart — its tightly guarded formula for ranking Web sites.

Google's system strives to elevate in search results the Web sites with content most relevant to a request. Because Google handles far more search requests than its rivals, its ranking system can make or break Web sites without a well-known domain name.

With the stakes so high, Web sites assigned a low Google ranking are constantly trying to elevate their standing, and an entire cottage industry has formed surrounding search engine optimization. Some sites resort to dirty tricks, hoping the shenanigans will fool Google into highlighting their Web links.

Google regularly tweaks its search formula to weed out the mischief makers — sometimes called "Black Hats."

In the worst cases, Google exiles the manipulative Web sites, a practice that has become known as being sent to "the sandbox" for the equivalent of a children's time out.

KinderStart's lawsuit alleges Google's policing efforts have penalized Web sites that have done nothing wrong. To make matters worse, the suit alleges the banished sites can't determine how they can restore their standings because the company doesn't explain its actions.

Mountain View-based Google has previously defended its right to revise its search formula however it sees fit.

In 2003, Google persuaded a federal judge to dismiss a case filed by Oklahoma City-based Search King Inc. after its search ranking abruptly fell.

Google argued its search ranking formula represented an opinion protected by the First Amendment, and U.S. District Judge Vicki Miles-LaGrange agreed.

This time, KinderStart is the one making accusations of free-speech violations — in Google's case, by reducing the traffic sent to Web sites that have been wrongfully punished.

KinderStart said its traffic plunged by 70 percent after Google dropped it. At its peak, KinderStart's visitors viewed more than 10 million Web pages per month, according to the suit.

Yu hopes to prove Google has become an "essential facility" that should be required to warn Web sites before dropping them from the index.

"We don't really feel there is enough transparency and openness in a service that has become so important," Yu said.

Google has always been tightlipped about how its search engine's works, maintaining the secrecy is essential to its success.