The military is using the FBI to skirt legal restrictions on domestic surveillance to obtain private records of Americans' Internet service providers, financial institutions and telephone companies, the ACLU said Tuesday. The American Civil Liberties Union based its conclusion on a review of more than 1,000 documents turned over by the Defense Department after it sued the agency last year for documents related to national security letters. The letters are investigative tools used to compel businesses to turn over customer information without a judge's order or grand jury subpoena. ACLU lawyer Melissa Goodman said the documents the civil rights group studied make us incredibly concerned that the FBI and DoD might be collaborating to evade limits" placed on the Defense Department's use of the letters. Goodman, a staff attorney with the ACLU National Security Project, said the military is allowed to demand financial and credit records in certain instances but does not have the authority to get e-mail and phone records or lists of Web sites that people have visited. That is the kind of information that the FBI can get by using a national security letter, she said. "That's why we're particularly concerned. The DoD may be accessing the kinds of records they are not allowed to get," she said. Goodman also noted that legal limits are placed on the Defense Department "because the military doing domestic investigations tends to make us leery.