I assume that person is talking about blood tests for suspected DUI's. >"All U.S. states have driver licensing laws which state that a licensed driver has give

I assume that person is talking about blood tests for suspected DUI's. >"All U.S. states have driver licensing laws which state that a licensed driver has given their implied consent to a certified breathalyzer or by a blood sample by their choice, or similar manner of determining blood alcohol concentration." -https://en.wikipedia.org/wiki/Implied_consent https://en.wikipedia.org/wiki/Implied_consent