Why do cops do that in America anyways? Isn't it much more secure to always use a breathalyzer. It only takes a few minutes and you can drive on.
I'm also quite sure that you could train for soberty tests (if they are as "unusual" as saying the alphabet backwards) when you're drunk so the cops think you're under the legal limit.
Because is you fail a "field sobriety test", it doesn't matter if you fail a breathalyzer, you get arrested for DUI/DWI anyway. So they do the field sobriety test first, then the breathalyzer after, so they have two chances of having a reason to arrest you.
But would their sobriety test hold up in court or what happens when you fail their field test (but pass the other test). If it doesn't hold up in court (because the scientific tests confirmed sobriety), why would they even bother doing both tests?
As far as I know, breathalyzer are far more accurate (less false negatives and positives). This makes me wonder why they would even consider doing the other test. They could catch actual drunk drivers with the time saved and have less work to do (because they don't need to file out paper work for sober drivers).