A coalition of liberal civil-rights advocates, conservative libertarians, gun-rights supporters and medical privacy advocates have joined forces to call on the government to overturn portions of the Patriot Act. Former Republican Congressman Bob Barr said that keeping the law intact would do “great and irreparable harm” to the Constitution. The group — the Patriots to Restore Checks and Balances — aims to overturn provisions of the law that allow government agents to carry out secret searches and to demand records from libraries, bookstores and medical offices.