Judging by the number of comments left, my last post left a bit of confusion. I believe I made my point clear enough the first time, but let me reiterate: no, I do not think that the police should spy on anyone unless they have reason to believe that their suspect is guilty of a crime. I believe that the Constitutional safeguards found in the Bill of Rights form a good, but not all-inclusive model for the safeguards that must be followed to prevent innocents from being harassed by the police. The proper level of precautions to follow is an empirical matter, depending on the nature of the crime (murderers should get more scrutiny that embezzlers, citizens more than foreigners) and the nature of the technology available to the police (with DNA, there is less need for eyewitness accounts.) Nevertheless, security and liberty cannot exist without the other.
By the way, it is inevitable that cops, judges, and juries will make mistakes. Innocents will be searched and convicted of crimes they did not commit, and perhaps even put to death for their crimes. Reason and evidence are rarely perfect, and that fact that mistakes will happen must be accepted as a given. The precautions and safeguards taken to prevent erroneous convictions will necessarily have to vary with the accuracy of the system, but the question of what amount of risk to tolerate, how many guilty men must be set free to prevent the imprisonment of one innocent is an ethical question that depends on the value one places on the sanctity of an individual human life versus the value one places on maintaining peace and order.
How does one weight the need to carry out justice versus the risk of punishing an innocent? I would say that the liberty of the individual must be placed first because it is its own end, while justice is only the means of ensuring it. Again, these are not mutually exclusive values, and I have yet to see a sound philosophical discourse on the topic. One thing that is clear however, is that the greater the accuracy of the system, the less guilty men will go free and the less innocent men will be punished.
Btw, what do you think of the background color changing to gray on mouseover? Should I just change the background to gray, or leave it white?
Also, please keep up the comments - I do find them entertaining, even if some of my readers (no names) need a good dose of reality.