And what would you do to replace the FSTs as part of an investigative tool to evaluate possibly impaired drivers? Let them go until they tag and kill someone? Mandate that they submit to roadside chemical rtests with instantaneous readings so as to avoid the song-and-dance of the FSTs? What?
ANY statement you make can be used against you at trial. The question is not whether the statement can be used, but whether a jury can be instructed or informed by a prosecutor that such a refusal is tantamount to an admission of guilt. I believe that in most instances it is required to stand on its own and the jury can make whatever conclusion it chooses to.
To NOT allow the question in, or the response, would be to carving out a special exception solely for DUIs ... and would require editing a lot of videos when that question is asked - in the case of a refusal, asked repeatedly.
The police can certainly try to convince you to take the FSTs. Refusing to take the FSTs can and almost certainly would also be presented to the jury, but the defense would also use that to show that the prosecution lacks sufficient evidence or to try and argue that without the FSTs there was a lack of probable cause for the arrest (which would be an issue outside the jury as part of a suppression motion). Usually that's simply not the case as many times we have enough just watching the driver in the car or when he steps out of the car (or the one guy I had many years ago who proceeded to ignore me, turn and urinate on his tire, and fall over. At trial the defense made hay of my lack of FSTs on the guy ... until the DA asked me why I did not do FSTs on re-direct.
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I repeat - you're incorrect.