How is it voluntary if you are arrested if you don’t agree to perform them??
Michael’s answer: FSTs are ABSOLUTELY voluntary and a driver should never agree to perform them. That said, the law on whether such a refusal is admissible at trial is unsettled. And law enforcement has become very adept at playing what I call the “Voluntary FST game”. Unlike constitutional rights, except for the portable breath test (PBT), the officer is NOT required to specifically warn the driver that they can decline to perform FSTs. They cannot order, command or otherwise compel a driver to perform them but they don’t have to tell the they don’t have to. Generally, they will simply work the word “voluntary in there somewhere (“I’m going to have you come over here and do some voluntary field sobriety tests to make sure you are OK to drive”) and most judges accept that as sufficient. They won’t like it if you assert your right to decline to do the FSTs and will probably arrest you any way, but you are at least denying them evidence they can and will use against you at trial.