This is it.

A FST is an investigation where a Breathalyzer is a search

In the US, no matter what state you are in, it is your constitutional right to not be searched without either a Warrant signed by a Judge, or probable cause which would make the search "reasonable"

Also, most lawyers would tell you to not consent to either if you know you are drunk. Just very politely refuse and let the officer do his/her thing.

If you are drunk and you submit to them, you are going to jail that night, and you are going to get convicted and face all the wrath that is a DUI.

If you don't consent to the tests, you are going to jail that night, but there is a much higher probability you will not receive the DUI. You may face losing your license for a year or even a fine for some other BS, but it's still WORLDS better than a DUI.

And if you don't consent and get convicted, it's still the same DUI that you would have gotten had you consented, well, mostly anyways. Some states have harsher punishments for DUI convictions where the driver refused the tests, but if you have a decent lawyer 99% of the time your sentience will be the same in the end.

You have to keep in mind that the vast majority of Judges are ex lawyers, meaning that they know exactly why you refused and they most likely during their career advised people to refuse. And the DA is all about convictions, they know that the probability of them getting the conviction is much lower since you refused so there is a higher chance that they will give you a plea that is lower, like "impaired driving" or something similar just so they can still get their conviction, again, a good lawyer will be able to work that out for you.

But the best way to not get a DUI is; DON'T FUCKING DRINK AND DRIVE