How We Lost Privacy: Today people are shamed for not sharing personal information about themselves.

• Author: Gulliver, Katrina
• Position: BOOKS - Sarah E. Igo's "The Known Citizen: A History of Privacy in Modern America" - Book review

A COUPLE OF YEARS ago, I went to dinner at the Seattle Space Needle. To my surprise--I was over 30--the waiter asked to see ID when I ordered wine. I hadn't brought my purse from the hotel, so I had nothing with which to prove my age. In retrospect, this probably saved me from a $100 bar tab at their prices, but at the time I was annoyed.

Although we aren't officially required by law to carry identification, in practice it is necessary to get through many interactions. This has become increasingly true over time. As a teenager I bought booze without problems. I can also recall being able to fly domestically without showing ID. I still often go out with nothing but some cash in my pocket. Nonetheless, like all of you, I leave a paper trail of account numbers, credit scores, and biometric photos wherever I go.

In The Known Citizen, a highly readable new history of privacy in America, the Vanderbilt historian and legal scholar Sarah Igo offers insight into the ways attitudes have evolved as different forms of identification, and different expectations of privacy, have emerged.

When future Supreme Court justice Louis Brandeis conceived of privacy as a "right to be left alone" in the Harvard Law Review in 1890, he meant a right to be free from intrusive media attention. The state's attentions were less of a concern to him. The inflection point, the time when privacy advocates focused their attention on the federal government, was the New Deal.

Social Security numbers presented a major issue for anyone who saw government registration as an infringement of civil liberties. But as Igo shows, linking Social Security clearly with the benefits to be garnered from registration turned most citizens in favor of the idea. Being enrolled in Social Security showed that one was gainfully employed, an upright citizen. In the early days of the system, some people even chose to have themselves tattooed with their number.

The government promised that the numbers would be used only for Social Security purposes, but they soon crept into different federal agencies' files, becoming, just as skeptics had feared, a general means of identifying citizens. Since the 1980s, Social Security numbers have been widely issued at birth; an entire generation of Americans have now lived their entire lives with open federal files.

AS THE PUBLIC became more relaxed about Social Security numbers, privacy concerns shifted elsewhere. After the Second World War, Americans pursued...