Before the American Revolution, British soldiers entered the homes of colonists at will, searching any person or place they wanted and often motivated by nothing more than political animosity. Resentment of this practice was a significant cause of the Revolution. Many Englishmen also objected to "General Warrants" authorizing searches at the discretion of the authorities. William Pitt, addressing Parliament in 1763, famously said, "The poorest man may, in his cottage, bid defiance to all the forces of the Crown. It may be frail; its roof may shake; the wind may blow through it; the storm may enter; the rain may enter; but the King of England may not enter."

When America won independence, revulsion against such practices led to enactment of the Fourth Amendment, which prohibited searches unless government had some evidence that a crime had occurred and a good reason to believe that a specific person or place contained evidence of that crime. Furthermore, the reasonableness of the search was not to be left to the discretion of an individual policeman; a warrant was to be issued by an impartial magistrate.

The Fourth Amendment is an essential feature of the American legal system. Unlike totalitarian regimes, we place the burden on government to show why it should be allowed to search, rather than on citizens to demonstrate why they should be left alone. We begin with the premise that individuals are entitled to be left alone unless there is good reason or "probable cause" to intrude upon their privacy. It would thus violate the Fourth Amendment if police stationed themselves on a public street and demanded that every third person who passed by submit to a drug test, even if it could be demonstrated that a high percentage of those who lived in that neighborhood used drugs.

Courts allow the state greater leeway when dealing with adolescents, particularly in the public schools. They have not required probable cause, but until recently have required "individualised suspicion"–some reason, however slight, to believe that Sally, rather than Janey, is engaged in prohibited activity.

No more. Now, despite those well-known lines from the Tinker case, students do indeed leave their constitutional rights at the schoolhouse door, assuming they are allowed to enter the schoolhouse at all.

The 7th Circuit has affirmed a Rush County policy barring students from extracurricular activities like chess club or library club unless they agree to submit to random tests for drugs and nicotine. In Anderson, students who are expelled for three or more days for any reason will not be readmitted unless they take and pass a drug test.

What are we teaching these young people? We certainly aren’t teaching them to respect principles of American constitutional law. We aren’t teaching them that government power must be limited and its use justified. We aren’t even teaching them that it is bad to use drugs. We are teaching them that the ends justify the means, and that might makes right.