Here in the US, I don't think you can be convicted of drunk driving on the basis of those tests. They are just things that the trooper can do as a quick check to see whether he should bother taking you back to the patrol car for the BAC breath test, or back to the station for a blood test.

When the trooper does those tests, they aren't done "pass/fail", it's not like you have to be able to do everything exactly right. They're just activities to make you balance or use certain cognitive skills that are impaired when you're drunk, so that you'll show it more readily by swaying or slurring your speech.

My brother tells the story of having been pulled over when he had too much to drink, and the troopers' test was a finger dexterity test: Touch the tip of your thumb to the tip of each finger (on the same hand) in a 1234,4321 pattern repeatedly. Since my brother is a piano player, he passed and the trooper let him go.