The Civil Contingencies Bill will lay out the emergency powers available to the police in responding to terrorist incidents. It is also designed to streamline local and national responses to a possible outrage, natural disasters and other emergencies.
But ahead of the publication of the formal bill by Cabinet Office minister Douglas Alexander, members of parliament warned the government's plans have "potentially dangerous flaws."
Shami Chakrabarti, director of human rights group Liberty, echoed the concern about the draft bill.
"What we are concerned about is that the definition of an emergency is so broad that it could cover any contingency whatsoever," Chakrabarti said. "It gives far too much power to government itself to define what it considers an emergency.
"The previous legislation was actually quite specific about what is a civil emergency and what is not," she said.