If my blood drug test already resulted to negative, can they still take it somewhere else to be retested?

If your blood was sent to another laboratory and the results have not yet been returned there are two different paths you should consider. If you are currently in court on your case you should consider pulling your time waiver and setting your case for trial (especially if you KNOW there is something in your blood that will improve the prosecution's case), if your case hasn't been filed, keep your fingers crossed that the results don't come back until after July 17, 2013 when the statute of limitations for misdemeanor prosecutions expires. You should discuss this with your lawyer, if you don't have a lawyer, you need to consider hiring a DUI defense attorney, there are some facts that should help you get a good result.

Yes. that's the lab's protocol ONLY if the officer asks for additional testing. Otherwise, they test it for alcohol first and then stop if the alcohol level is over the legal limit. If the alcohol level is not over the legal limit there is a form that the officer checks that may lead to further testing or the lab supervisor may speak with the officer about the case. If your blood was drawn under "implied consent" then you should thinking about sending the lab a letter and withdrawing consent for further testing.

If the blood was maintained properly, it can be used for subsequent tests. If the second test should show the presence of prohibited drugs, you can still point to the first test to raise a doubt.