Why is it some people are unable to make their point and then let it stand instead of repeating, ad infinitum, their hypothesis without introducing something new to the argument?
Black Sword, your point is made but you haven't backed it up with any reference except your own, very basic interpretation. FL and bjcc have both mentioned that the (English) law, as it stands at the moment, does use urine testing to determine BAC. I don't know the reasoning or methodology that is used to make this determination but I'm sure that someone from the medical profession would be able to. In the meantime, please stop sounding your own trumpet as it is getting repetitive and not getting this debate anywhere.
Perhaps you would like to take your theory and prove it. Why not partake of as many units of alcohol that you can stomach, apply your assumed time limit for your liver to metabolise the alcohol, clench your bladder muscle as tightly as may be needed and then get your sample and blood tested at the same time? If you are so sure about your position, I'm sure you could persuade some organisation to sponsor you to cover the costs of doing this, especially if it will make the news.
In the meantime, please stop repeating your assertion that alcohol in urine testing does not not reflect BAC. Whether it does or doesn't makes not one iota of difference in the eyes of the law as it stands. Until you are prepared to prove otherwise, the matter rests.