Advances in technology often outpace the law -- and the law has to rush to catch up.
A current example can be seen in how some uses of Facebook and other social media are outrunning the law of privacy.
Facebook is a powerful tool for a person to communicate and share information with friends. As a user, you can keep all of this information behind a password-protected wall. Or, if you choose, you can make it public for the whole world to see (assuming the world would care). The important thing is: It's your choice.
In recent weeks, however, news reports have described instances around the country where employers have requested the Facebook passwords of job applicants as part of their hiring process.
The news has provoked a very strong response from Facebook users and from Facebook itself. Both the users and the company have been clear that they oppose this practice.
Asking for someone's password has been compared to demanding the keys to a person's home so someone can go in and search their personal belongings for anything they want. One of the scariest things about it is that it violates not only the Facebook user's privacy but also invades the privacy of all the user's friends.
The ability to control your personal information is one of the hallmarks of what we mean by "the right to privacy."
In 1890, before he was on the Supreme Court, Justice Louis Brandeis coauthored one of the most influential legal essays ever written, in which he formulated the modern concept of privacy, saying:
"The common law secures to each individual the right of determining, ordinarily, to what extent his thoughts, sentiments, and emotions shall be communicated to others. ... The existence of this right does not depend upon the particular method of expression adopted. It is immaterial whether it be by word or by signs, in painting, by sculpture, or in music."
It reads as though it could have been written today, and it would be easy to insert the words "Internet" or "Facebook."
In his own time, Brandeis was responding to the challenges of new technology, like instant photography, and new businesses, like mass-circulation newspapers.
Brandeis also described the right to privacy in much simpler terms. He called it "the right to be let alone."
Some Internet enthusiasts like to claim that privacy is dead in an online world, and good riddance. But, to paraphrase Mark Twain, the reports of privacy's death are greatly exaggerated.
Most Internet users don't feel they automatically forfeit their right to privacy just because they're online. In fact, a recent national survey by the Pew Research Center found that social media users are becoming more active in limiting access to their information.
Compared with 2009, a higher percentage reported deleting people from their "friends" lists, deleting comments made by others on their profile and removing their names from photos in which they were tagged.
The survey also found that women and young users were the most active in protecting their privacy.
So the idea that an employer is entitled to your personal Facebook account doesn't sit well with most people.
That's why I've introduced federal legislation with my colleagues Chuck Schumer of New York and Richard Blumenthal of Connecticut that would prohibit an employer from requiring that a current or prospective employee turn over the password to their Facebook or other online accounts.
This legislation would protect not only the Facebook user, but also the employer.
While technology may change, our most cherished values must not. Among these values is the right to privacy -- the freedom of each individual to decide who will know their "thoughts, sentiments, and emotions."
Amy Klobuchar represents Minnesota in the U.S. Senate.