A federal judge has ruled that Google Inc. must comply with the FBI's warrantless demands for customer data, rejecting the company's argument that the government's practice of issuing so-called national security letters to telecommunication companies, Internet service providers, banks and others was unconstitutional and unnecessary. ------ The letters are used to collect unlimited kinds of sensitive, private information, such as financial and phone records and have prompted complaints of government privacy violations in the name of national security. Many of Google's services, including its dominant search engine and the popular Gmail application, have become daily habits for millions of people. ------ It was unclear from the judge's ruling what type of information the government sought to obtain with the letters. It was also unclear who the government was targeting.