The key word being 'potentially.' Sex offenders and violent criminals can potentially go to jail for life. While the maximum penalty for this offense seems quite excessive to me, I can't really blame the police for simply quoting the statutory provisions. For one thing, there's a basic idea in criminal justice that people should be made aware of the risks they are running, known as constructive notice: http://en.wikipedia.org/wiki/Constructive_notice
Excessive punishment, even if it's a theoretical maximum is a travesty of justice.
Take a look at the USA where mandatory minimum sentencing [1] is in effect for drug offenses - once a ludicrous maximum is set, all it takes is another measure to put a more "reasonable" minimum and make it mandatory... the Overton window [2] principle applies very well here.
Mandatory minimum sentences (as most people think of them) were actually struck down by the Supreme Court seven years ago in US v. Booker (http://en.wikipedia.org/wiki/United_States_v._Booker). The legal arguments are technical and sentencing policy remains something of a gray area. An excess of leniency in past decades led to an excess of punishment later, and inconsistencies in sentencing standards led to the creation of a national commission to establish uniform sentencing guidelines, which were then struck down in Booker for being too inflexible. It's a complex problem, not least because there's no objective metric for deciding what is 'excessive.' For that matter, there isn't even much consensus on what is effective.
I'm well aware of these stats. the problem is that the proponents of heavy sentencing are apt to claim that crime is going down because the increasingly tough sentencing keeps more criminals off the street for longer periods as well as having a deterrent effect. I don't find this very persuasive, but I've have to go into some details about the law of criminal procedure to say why; nor do I have a clear alternative policy to suggest.
Economic theory as applied to criminal suggests that sentences must be harsh in inverse proportion to the probability of catching a given criminal, in order to eliminate the 'producer surplus' of crime (potential gain/ (potential risk of capture * loss of sentence)). Of course, the weak point of this theory is that law enforcement has a strong economic incentive to prosecute easy-to-prove crimes like drug possession; another issue with it is that the public perception of crime risk and severity isn't very well correlated with the actual risk, and historically people are not very interested in what happens to criminals after conviction.
Since the costs of a trial are so high, most investigations result in a guilty plea in exchange for a reduced sentence and the public cares even less about people who say they are guilty. The public is somewhat interested in the claims of the innocent, but then again many assume that there's no smoke without fire and resent defendants' use of taxpayer-funded resources to conduct long trials and lines of appeal. American law is so procedural that trials are very very slow compared to most other countries, and so expensive and challenging for both prosecutors and defense lawyers that only fewer than 5% of charges go to a jury trial; the rest are settled with plea bargains, bench trials and so forth.
See http://www.marcgalanter.net/Documents/papers/thevanishingtri... page 462 onwards. Clearly the current system is not working well at all and is creating a great many injustices of its own, but there's very little legislative mileage in saying that. I was quite surprised that Congress passed the legislation eliminating the disparity in crack/cocaine sentencing in 2010, given that crack dealers have been the criminal bogeymen of choice for so long.
