Should it be?

Yes it should be a deterrent as crime prevention is better than crime punishment, irrespective of whether you're the criminal, victim, or taxpayer.

Prison should also be a deterrent. Reoffending rates are far too high (in my country). Whether prison is meant to deter or rehabilitate it should ensure that everyone who leaves prison shouldn't consider going back. If prison can't deter the people who've been inside then how can it deter anyone else?

Silly questions.

Of course it's a deterrent to crime; if we abolished all criminal laws tomorrow, few would argue that there wouldn't be a massive criminal rampage (at least until the civilians become a private police force).

And of course it <i>should be</i> a deterrent to crime; of the four aims of punishment (the other three being incarceration, rehabilitation, and retribution), it's the most useful one, because by deterring a crime we can prevent the harm before it occurs, for little cost.

The more interesting question is, are the current laws a <i>sufficient</i> deterrent, and the answer is a spectrum from "yes, way too much in fact" to "no way", depending on the specific crime.

For example, many drug crimes are over-deterred by the current punishments, whereas many corporate white-collar crimes are under-deterred.

It most certainly is a deterrant. If it weren't for the law I'd have shot some of the folks on this board years ago.

What the **** ever happened to Fairweather Pure anyways?

Should it be?
In most cases, yes. It shouldn't be used as a deterrent for drug users though. If someone is using drugs (any drugs) and not breaking any other laws then they should be left alone. If they are committing crimes to support their habit then bust them and punish them for those crimes but leave the drugs out of it. Putting an otherwise non-criminal drug user in prison is the pinnacle of stupidity. They're forced to associate with real criminals and are more likely to become one themselves than they are to rehabilitate.