Actually, the LDT has zero legal value in New York, a Frye State. (
link ) Recall, the Frye standard is the result of a precedent setting 1923 case (
Frye v United States, 54 App. D.C. 46, 293 F. 1013 [1923],
link ) as it pertains to expert testimony. In fact, Frye v US involved an attempt by the defendant to exonerate himself due to the results of an LDT.
Even so, LDTs, if properly applied, can still be useful when trying to rule people in/out as a POI. Though, not for the reasons commonly thought. In reality, their passing/not passing has not a thing to do with... well, anything. That is, outside of, perhaps, making them sweat... and, if guilty, pushing them in the direction of confessing to a crime.
Otherwise put, it is the psychology behind the LDT that can be useful. Otoh, if that psychology is improperly applied, then you end up with cases like Riley Fox, where the dad actually confessed to a crime he did not commit. (
link )