Protect Me
The role of government has bloated far beyond what it should be. The government shouldn't be in the business of protecting people from their own stupidity, only the stupidity of others.
I'm Stupid
Let's say, for example, I want to try and fly off the roof of my house. Supposing there are no small children down below, the only person I am going to hurt is myself. Now, the question is, should my government attempt to stop me?
No, they shouldn't; I should be allowed (encouraged, even) to make my own decisions in the area of roof-jumping. Certainly, education programs revealing the dangers of flying off one's roof would be useful, but people with nets standing around buildings waiting to arrest roof-jumpers is certainly not the type of society I want; governments shouldn't protect me from my own stupidity.
You're Stupid
In a related example, lets suppose that you've heard jumping from great heights into other people's houses is great fun. Should you be allowed to pursue your pleasure, as I did? In this case, no, as you jumping into my house could very well injure me. The government should attempt to stop you, as you're very likely to injure me.
We're Both Stupid
Of course, referring to the preceding example, if I gave you prior permission to defile my residence, by all means you should go right ahead. If we're two consenting adults, the results of our actions are our own concern, not that of the government (or society in general).
This is Stupid
There are, of course, a number of problems with even the simple scenarios presented above. A number of grey areas exist between things which clearly only harm the person involved (i.e. roof-jumping from a barn) and actions which generally only harm the person involved, but might (in rare circumstances) harm more people (i.e. roof-jumping from an apartment building to a crowded street).
There is also the issue of harm; what exactly causes harm to someone else? Is psychological harm enough? Monetary? Indirect monetary harm? For example, there is universal health care here in Canada which everyone must pay for. If someone hurts themselves, everyone indirectly pays for it. This is not an argument for limiting people's actions; perhaps diets should be regulated, as high-fat diets result in an increased risk of heart disease.
The issues of harm must also be balanced against the question of what exactly freedom is. If you are "harming" someone else, then it's "bad". Otherwise, go for it. Consideration must also be given to prior consent: how do I prove that prior consent was given? Is a post-it note written in crayon good enough? A verbal agreement? A signed, witnessed legal document? It depends on what took place.
The Verdict
The bottom line is, governments (or law, or whatever) should be allowing people to do whatever they want, as long as they aren't "harming" someone else. If prior consent was given, anything is fair game. Of course, it is up to judges to decide what type of consent is reasonable for the situation and what, if any, harm might have taken place as a result of the actions.
This is all really vague, as is much of our law, but I think people today are a little too quick to blame others for their unfortunate accidents and problems. Law, especially criminal, must move away from blaming people for doing things which harm only themselves or other consenting adults. In a nutshell, "chill out" and don't blame the sidewalk for breaking your fall.