The title of [Baker's] new book refers to accelerating technological change and the new dangers it's creating. Our society is advancing, technologically, at a very rapid clip; but so, unfortunately, are the terrorists. 'It's like skating on stilts that get a little longer each year.' he writes. 'Every year we get faster and more powerful. Every year we're a little more at risk. We are skating for a fall, and the fall grows worse every year.'

That prognosis is more than a little unsettling, given Baker's resume©. As general counsel to the National Security Agency (the Pentagon's foreign electronic-surveillance arm) during the presidency of George H. W. Bush, he was a staunch privacy advocate. As policy chief at the Department of Homeland Security during that of George W. Bush, he spent years locked in a tug-of-war with privacy advocates over every initiative to adjust our security strategies.

If Baker is not precisely a pessimist, he is certainly gloomy; but even the most optimistic national-security official would find himself chronically dispirited by the effectiveness of the constituencies arrayed against all efforts to devise new ways of protecting ourselves from terrorists. Baker's book is a treasury of examples.

The book recounts some important successes, and in his unremitting gloominess Baker is almost certainly guilty of not giving himself, or the Bush administration, quite enough credit.

Are we doomed to suffer another major terrorist strike? For some, it seems like a remote possibility, with the greater danger lying in policies of hyper-surveillance. For others, the real danger is complacency—the assumption that the threat has passed—and a misplaced eagerness to scale back the policies that have kept us safe for nine years.

One man who has pondered this question from a pivot point in the federal government is Stewart Baker, a general counsel of the National Security Agency in the Clinton years and a policy chief in the Department of Homeland Security under George W. Bush. With Skating on Stilts, he offers a memoir of day-to-day life within a major Washington bureaucracy and an insider's analysis of the challenges to domestic security in the post 9/11 era.

Skating on Stilts is full of such anecdotes, and Baker, who was a key Homeland Security player from 2005 to 2009, makes a persuasive case against the privacy absolutists. He reprises his successful effort to pry airline passenger data out of the Europeans, who are even more uncompromising about privacy than American activists. He tells the story of how the wall erected between intelligence-gathering by the FBI and law enforcement, though designed to protect civil liberties, ended up blinding authorities to the unfolding 9/11 plot. And he recounts how other agencies blocked, on privacy grounds, DHS' bid to maintain and update a database to continually screen the backgrounds of scientists who work with deadly biological pathogens.

Baker deftly skewers the original legal theorist behind the right to privacy, Supreme Court Justice Louis Brandeis, who was scandalized in 1890 by the fact that newspapers published flattering details about a party at his house. Brandeis also found it outrageous that a newspaper could take and publish a photo of a person without his permission. Obviously, the idea of what constitutes an invasion of privacy has evolved dramatically. Baker portrays privacy advocates as fussy Luddites.

When the government collects information about people, Baker acknowledges, some bureaucrats may improperly access it, as when State Department employees rifled Barack Obama's passport file during the 2008 presidential campaign. But the employees were easily caught and disciplined, Baker notes. The answer is to hold bureaucrats accountable for abuses, he says, not deny them important security tools.

The events of 9/11 were caused as much by technological change as by evil men and government errors. From jet travel to the Internet, technologies that empower ordinary individuals will sooner or later also empower Osama bin Laden. When technologies grow exponentially, unintended consequences are inevitable. Government needs new tools to respond to these emerging threats. But no is still the privacy community's default answer to any improvement in law enforcement technology. Anything government proposes to head off the risks of new technology faces bitter diplomatic, privacy, and business resistance. In this book, Stewart A. Baker--the first assistant secretary for policy at the Departmen of Homeland Security under the Bush administration--draws on his experiences in government to illuminate the ongoing battle between proponents of privacy versus those of security.

The author describes how civil liberties rules cost us our last, best chance to catch the 9/11 hijackers before they struck. He shows how Homeland Security is transforming border security to meet the challenge of exponential increases in jet travel. And he looks at the European Union's opposition to this transformation, cautioning that if Europe's first inclination is to slow the Americans down, question their motives, and make them pay for any changes in policy, we will not be able to meet the challenge of other accelerating new technologies. He examines how a left-right privacy coalition--including such strange bedfellows as the ACLU and the Gun Owners of America--blocked changes at the Transportation Security Administration that would have both made travel easier and stopped the "Christmas Day Bomber."

Turning to other exponential technologies that carry new risks, Baker examines the rise of "Moore's outlaws"--those who use the growth of information technology to spy, steal, and wage war in cyberspace--and the democratization of biotechnology that will make it possible for garage biohackers to reconstruct smallpox and worse in garage labs.

We can avoid the worst risks, concludes Baker, if we take action early. But with privacy campaigners fighting all new government uses of technology, early action is nearly impossible. What's needed is a view of privacy that embraces the future instead of trying to keep law enforcement in the 1950s until disaster strikes.