There’s been a recent change in the law of the Supreme Court decision that decided I believe in late 2013 that declared statutes that required blood sample after an accident; if the cop suspected the individual of being intoxicated. It was actually regardless of whether you consent to it or not. The cop could can administer that. The Supreme Court said that’s too much of an invasion of your own personal privacy. You’re talking needles into your arm. So they upheld the right even in those circumstances to not consent to a blood test.
For more information on blood testing and DWI cases, learn about what to do when stopped for DWI, explore breathalyzer tests, and understand field sobriety tests. You can also visit the NHTSA for official information on impaired driving laws.