Michael Chertoff was one of the main legal architects of the war on terrorism. He is now President George Bush's choice to lead the Department of Homeland Security. National Correspondent Jim Malone has more on Mr. Chertoff and the challenges he faces from Washington.

Michael Chertoff

Michael Chertoff, 51, is a veteran prosecutor and Justice Department official who has served as a federal appeals judge since 2003.

Judge Chertoff was in charge of the Justice Department's criminal division at the time of the 2001 terrorist attacks. He played a key role in shaping the legal response to the terror attacks that included detaining hundreds of immigrants suspected of links to terrorists. Some of those suspects were deported while others were eventually released.

George Bush, left, speaks during announcement of Chertoff nomination

President Bush paid tribute to Mr. Chertoff's experience in the war on terrorism when he announced his nomination.

"I am grateful that the judge has agreed to bring his exceptional judgment and integrity to an urgent new responsibility," he said. "I am confident that he will be a strong, effective leader for the Department of Homeland Security."

If confirmed by the Senate, Mr. Chertoff will succeed the first Homeland Security secretary, Tom Ridge, who is returning to private life.

Mr. Chertoff says he is aware of the enormous challenges he faces in leading a department that was created by merging 22 different agencies into one Department of Homeland Security.

"They secure our ports and our airways, our borders and our buildings, our computers and our public utilities," he said. "They respond to natural and man-made disasters in our hours of greatest need."

Initial reaction from members of Congress was generally positive. Democratic Senator Frank Lautenberg of New Jersey called Judge Chertoff one of the most able public servants he has known.

Republican Congressman Chris Cox of California also welcomed the Chertoff nomination. But he also had some advice about national security priorities in an interview on NBC television.

"At the top of that list is the long-run potential of terrorists acquiring nuclear weapons or terrorists acquiring biological weapons and the means to use them," he said. "We have simply got to prevent that from happening."

Security experts were quick to praise Judge Chertoff for his intellect. But some also cautioned that he has never run an agency this large before.

"He is a very highly respected judge," says Michael Greenberger, a security analyst at the University of Maryland. "Very smart, very thoughtful. He certainly is not tested in dealing with a large bureaucracy."

Mr. Chertoff does have his critics, especially in the area of civil liberties. Many civil liberties activists were critical of the Justice Department's round-up of immigrants suspected of terrorist links in the wake of the 2001 attacks.

Judge Chertoff defended the detentions during a Washington forum on terrorism laws in 2003.

"Even if it were true that only a fraction of the people picked up under this lawful process actually posed a danger, would it have been responsible for the administration to take the opposite position? To let them all go on bail because you do not have enough to prove a case beyond a reasonable doubt? And then, if one or two decided to blow up the Lincoln Tunnel and a couple of thousand people were killed, would the next 9/11 commission say that is a great choice," he said. "Let us keep it up? Or would people say the government was not behaving appropriately?"

Judge Chertoff is the president's second choice to replace Secretary Tom Ridge. Former New York City Police Commissioner Bernard Kerik abruptly withdrew his nomination last month after questions were raised about the immigration status of a family housekeeper.