A broad coalition of technology companies, including AT&T, Google and Microsoft, and advocacy groups from across the political spectrum said Tuesday that it would push Congress to strengthen online privacy laws to protect private digital information from government access. The group, calling itself the Digital Due Process coalition, said it wanted to ensure that as millions of people moved private documents from their filing cabinets and personal computers to the Web, those documents remain protected from easy access by law enforcement and other government authorities. The coalition, which includes the American Civil Liberties Union, the Electronic Frontier Foundation and the Center for Democracy and Technology, wants law enforcement agencies to use a search warrant approved by a judge or a magistrate rather than rely on a simple subpoena from a prosecutor to obtain a citizen's online data. The group also said that it wanted to safeguard location-based information collected by cellphone companies and applications providers. forcement agencies and the Obama administration.