What is Consent?

Definition Round Three!  So, consent, Google dictionary says "Permission for something to happen or agreement to do something."

 Unfortunately, it's not that simple.  There are a whole plethora of complications when it comes to the application of consent, and sometimes although you "actually" consent, you "legally" do not.  The example I'm going to use for this is the example that was used at the Cambridge Open Day in the Law sample lecture.

I have £1, and you need to borrow it from me.  I know that you always play the lottery on a Friday (and in this hypothetical situation, it is Friday) and I also know that you left your wallet at home.  I can gather that you're ashamed that you're playing the lottery with my money, so I'm still happy to give you my pound coin even though you told me that you needed to buy a birthday card for your mum.  I feel that I'm consenting to you using my money to buy the lottery ticket, even though you're currently lying to me.  In fact, by giving you the £1 despite knowing that you're lying, I'm making you a thief - as there was an attempt to mislead me, and I was "cheated" out of my money.

In fact, I'd be doing you more of a favour if I randomly gifted you my money.  The premise of borrowing makes matters even worse.  It would be seen as stealing if you didn't give me that exact pound coin back, as the law doesn't allow for  exchange of similar or equivalent property.  The intrinsic value of the money is superfluous, as I had specific ownership over that exact £1, and the law would expect for me to receive it back. 

This makes sense, if you think about it.  If you were to lend me your car, and I brought back a different car of the same value, you wouldn't be too happy, would you?  (Let's presume this is a particularly unattractive car).  So, for the law to protect your rights over your property, it has to count for the small things as well as the big things.

And even then, when does consent count in the first place?  You might consent to me chopping your arm off for no reason, but that doesn't mean that I'm not going to be prosecuted for it.  There is some area where the law protects us from things that we may have given consent to.  This idea is about a paternalistic government is condemned by those of a liberalist standpoint, as the restriction of freedom should be avoided in all circumstances.  This would mean then, that the condemnation of sado-masochistic activities would be seen as wrong, although by mainly liberalists.

Despite this, consent is still questioned or challenged in court every day.  Yes, the old man with dementia did give "consent" to the blonde money-grabber to empty his bank account - but should that have been allowed to happen?  Consent only matters if it was informed and non-destructive, I can gather - but should the government ever have a right to interfere in your choices, or claim that you were incapable of making them?

Your thoughts please :)