Nolle prosequi is a Latin legal phrase meaning "to be unwilling to pursue" a Latin construction that amounts to "please do not prosecute". It is the term used in many common law criminal jurisdictions to describe a prosecutor's application to discontinue criminal charges before trial, or up until, but before verdict.
Nolle prosequi is a declaration made by a prosecutor in a criminal case either before or during trial, meaning the case against the defendant is being dropped. The declaration may be made because the charges cannot be proved, the evidence has demonstrated either innocence or a fatal flaw in the prosecution's claim, or the prosecutor no longer thinks the accused is guilty, and/or the accused has died. It is generally made after indictment, but is not a guarantee that the person will not be reindicted.
In a criminal case, it has been held improper for a court to enter an order of nolle prosequi on its own without a motion by the prosecutor. As long as a jury trial has not been commenced, the entry of a nolle prosequi is not an adjudication on the merits of the prosecution, and the legal protection against double jeopardy will not automatically bar the charges from being brought again in some fashion.
Nolle prosequi is similar to a declination of prosecution, which is an agreement not to prosecute which may be made by an attorney, but also by the aggrieved party. In contrast, nolle prosequi is usually made after a decision to prosecute has already been made. A declination of prosecution may be made for many reasons, such as weak evidence or a conflict of interest.
Essentially it means that the case has been dismissed but it can be refiled if the State receives the blood test within the statute of limitations (which is running when the case is dismissed.) This is a good thing, although in the long run it may be more like a long reset than a dismissal.