AFTER an investigation that took more than a year, Microsoft has filed its first lawsuit over click fraud, where people manipulate clicks on a Web advertisement.

Microsoft filed the civil complaint on Monday in United States District Court in Seattle against Eric Lam, Gordon Lam and Melanie Suen, of Vancouver, British Columbia, along with several corporation names they were believed to have used, and several unnamed parties.

Microsoft is seeking at least $750,000 in damages. That might seem a small amount for a company that had sales of $13.7 billion last quarter. But about one in every seven clicks on an advertisement is estimated to be fraudulent, according to the traffic analysis firm ClickForensics, and Microsoft is trying to make that kind of deception more expensive for perpetrators.