I think that this is a very grey area of the law, which is essentially how it's treated in the Australian legal system anyhow. I don't think it's really possible to pinpoint any age and say that at that time, one should definitely be tried as an adult. At the moment that point is 18, but it's right that if someone is 16 or 17 and commits a murder, then in most cases they should be tried as an adult... So if the law is changed to say that at 16 someone should be tried as an adult, then what do you do about the 15 and 11 month year old who commits a serious crime - surely they should also be tried as an adult?
The truth is that while some 15 or 16 year olds are mentally mature enough to be tried as adults when they commit these crimes, others certainly aren't. Given that, I don't think it would be appropriate to lower the age limit. I think what should happen, and it already kind of does in Australia, is that it should be taken on a case-by-case basis. To be convicted of a crime under Australian law (the specifics differ between each state and territory somewhat, but it's possible to generalise still) you must have firstly committed the physical act (i.e. killed someone), and secondly have possessed the appropriate mental state (i.e. intending to kill someone). So if I were to accidentally hit someone with my car and kill them, phsyically it would have been my actions that killed them, but as I had no intent to kill them I would not be guilty of murder (although if I were doing something like driving 'recklessly' then I might be guilty of manslaughter - but that's a different story). My apologies if everyone already knows this, but it helps me get to my point...
So given this requirement for an appropriate mental state, if a 15 or 16 year old was to kill someone, for them to have this requisite mental state it would require that they were fully aware of what they were doing is wrong. Most people of that age group would know that killing people is wrong, but there are always going to be exceptions. Murder is one of the clearer categories - everyone knows that killing someone is morally repugnant - but crimes such as rape or theft or reckless driving are not so clear cut. If a 15 year old was to have sex with someone without consent, it would be easily arguable that they were not fully aware that what they were doing was really that wrong, or likewise with taking a car on a joy-ride - they were just doing it to have a bit of fun, and really didn't mean any harm.
The other issue is that some of these crimes carry very hefty penalties, and it would be tragic to see kids of age 15 being locked up for up to 20 years because of something stupid that they did at that age. In this sense, I suppose it would be reasonable to try minors as adults, but just take things into consideration when sentencing - like age, and likelihood of reoffending. I think at that age, kids certianly deserve a second chance, especially if the crime was taking a car for a joy-ride or something (as opposed to something more serious like murder).
And I think that absolutely parents have something to answer for, within reason - I don't think that, for example, a parent should be punished (like, jailed) for something that their child has done. Rather, that when children offend, it should be the whole family situation that's looked at, and perhaps the parents be forced to attend counselling also or something.
I'm sorry for my round about post - on the whole I agree with what people are saying, minors should be able to be tried as adults, but really I think it needs to be taken on a case-by-case basis.
