Drugs

Specifically the crucial distinction between illicit and prescription only.

Both have great potential for abuse, both are abused on a large scale, and both have physically harmful and chemically addictive variants.

What is the difference that warrants the legal distinction between these drugs? The primary stated reason is the lack legitimate medical uses for the illegal drugs. In most cases this claim is highly questionable; I won't go down the list here, but the majority of illicit drugs have or have had accepted medical uses, and almost all of them have some potential, if only very slight (Feel free to provide counterexamples; I am honestly curious about this).

There are two glaring differences between them;

The first is the way in which society perceives the drug. There is a more significant and widespread stigma associated with the use of illegal drugs than there is with legal ones. Some of this is due to the stigma associated with crime in general, and some of it has to do with use of the drugs themselves regardless of law. What is considered popular or acceptable to society is meaningless when one is considering what the best thing to do is.

Secondly, and more importantly, is the price of illegal drugs, which creates a massive, extraordinarily profitable, and violent business built upon their sale - the highest cost of prohibition in terms of corruption and human suffering.

I've rambled a bit, but perhaps you've taken my point; why make some drugs illegal and others available by prescription if both are addictive and harmful? Why is opium legal and heroin illegal?

Drug law ought to be based on chemistry and medical science; instead it is and has been based on popular opinion, public fear, and as a reaction to the other criminal acts of those who sell them.