The United States Supreme Court decision in Birchfield v North Dakota dramatically changed DUI defense in PA. Prior to that decision, law enforcement didn't need a search warrant to obtain your blood sample. After Birchfield however that all changed. Now to take your blood, police need a search warrant. Without a search warrant, the results of the blood test are inadmissable in court. What that basically means is the Prosecution can't use that against you.
The severity of a DUI in Pensylvania, like most states, depends on a person's Blood Alcohol Concentration and as a person's Blood Alcohol Concentration (BAC) increases, so does the DUI penalties. So if blood evidence is inadmissable, it really hinders the prosecutions ability to prosecute you on more serious DUI offenses. It isn't to say you can't be prosecuted, but the blood evidence, or the lack of it, prevent the prosecution from introducing that evidence against you at trial.
Now please keep in mind the Birchfield decision did not affect the use of a Breathalyzer, so police do not need a search warrant to take your breath sample. The reason why is because the Supreme Court in the Birchfield decision said that the taking of a person's blood is much more intrusive than a breath sample or breathalyzer. With a blood sample, law enforcement or the government or in the case of Pennsylvania, the Commonwealth is actually piercing your skin to obtain a sample of your blood.
For more questions about DUI defense I encourage you to read my book "Five Ways to Fight & Win Your Pennsylvania DUI Case". It's available on the website and it provides great information for a person facing a DUI situation.
I look forward to seeing you in the office.