What is the legal test for negligence in a criminal proceeding?

"Barker made it clear that 'different weights [are to be] assigned to different reasons' for delay. [Citation.] [39 Cal.App.4th 1731] Although negligence is obviously to be weighed more lightly than a deliberate intent to harm the accused's defense, it still falls on the wrong side of the divide between acceptable and unacceptable reasons for delaying a criminal prosecution once it has begun. And such is the nature of the prejudice presumed that the weight we assign to official negligence compounds over time as the presumption of evidentiary prejudice grows. Thus, our toleration of such negligence varies inversely with its protractedness, [citation], and its consequent threat to the fairness of the accused's trial." (Doggett v. U.S. (1992) 505 U.S. 647, ----, 112 S.Ct. 2686, 2693, 120 L.Ed.2d 520.)