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Fourth Amendment and Privacy

The Fourth Amendment to the U.S. constitution is designed to protect citizens and their property from invasion by the government.   In its entirety, it reads,

“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”

The question now is how to interpret privacy in a modern setting, when cyberspace makes information increasingly more public and the definition of papers and effects are different than what the founding fathers could have conceived.

With social networking sites such as Twitter, Facebook, and Formspring, individuals choose to release information about themselves every day.  Conversations over instant message programs like Skype and AIM can be intercepted.  Data can be encrypted, but does that add to Reasonable Expectation of Privacy ?

How do privacy and the Fourth Amendment apply to cyberspace?

What are the current Fourth Amendment trends?

The Fourth Amendment essentially splits your life into two sections: What you do in public, and what you do in the privacy of your home.  In order to understand the Fourth Amendment and cyberspace, it might be helpful to look at how it affects other aspects of life. 

For our purposes, we are going to look at a website appropriately titled “Cyberspace law for non-lawyers.”  Posted on this site are numerous short articles by Larry Lessig, David Post, and Eugene Volokh.  Thirteen articles are on cyberspace privacy; here we take an excerpt from the second and third articles, which look at how well your informational privacy is protected.  They define information privacy as “the collection, and dissemination, of information about you that you have willingly given over to someone else.” Article 2

“But [the Fourth Amendment does not protect the privacy of] what books you check out at the library, or what your purchases at the grocery store are, or what movies you use your credit card to buy tickets for. These remain unregulated by the law.” Article 2

The reason for this is that the Fourth Amendment mostly protects information you don’t make public.  Once you put it in public view, you no longer have a reasonable expectation of privacy.

Does privacy extend to data encryption?

In the modern age it is easy to encrypt files with free programs.  If your friend has the same ‘key’, it is just as easy for them to decrypt the message and read it.  Without the key, unlocking the message could be very difficult.  Given how hard it is, does the Fourth Amendment protect the privacy of data you encrypt?

A scholarly paper written by Orin Kerr, which you can find and read for free here, postulates that decryption of encrypted data does not violate the Fourth Amendment.  Orin’s argument stems from the fact that when using encryption, the user risks the chance someone will take the time and effort to decrypt it.  When the cipher text or encrypted data is transmitted, it is essentially made public. If the government attains this data in a legal way, what they do with it afterward does not violate the Fourth Amendment.  For further examples, we encourage you to browse his paper.

Orin Kerr’s argument is also backed by court rulings from 16th century England up to modern day cases.  In 1586, during the trial of Mary Queen of Scots, key evidence included letters sent between Mary and a group of conspirators who were attempting to assassinate Queen Elizabeth.  Before being used to condemn Mary in court, the letters were decrypted by a famous code breaker.  More modern cases include United States V. Longoria, were a message was ‘encrypted’ in Spanish, again assuming that no one would spend time attempting to decipher or translate it.  The court ruled that translating something into a foreign language does not create Fourth Amendment protection.

Other cases Orin cites are United States V. Katz, Rakas V. Illinois, United States V. Scott, United States V. Sarda-Villa, and Commonwealth V. Copenhefer.

How do privacy, the Fourth Amendment, and cyberspace apply to you?

As we covered in the earlier sections, information you choose to make public cannot be protected by the Fourth Amendment.  So, when you post something about yourself on Facebook or Twitter, know that what you are saying is available for the world to see.


Kerr, Orin S., The Fourth Amendment in Cyberspace: Can Encryption Create a Reasonable Expectation of Privacy?. Connecticut Law Review, Vol. 33, p. 503, 2001; GWU Law School Public Law Research Paper No. 219; GWU Legal Studies Research Paper No. 219.

Lessig, Lawrence, David Post, and Eugene Volokh. "CyberSpace Law Lessons." 23 Sept. 2007. Web. 04 Apr. 2011. <>.

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