The 6th Amendment to the Constitution guarantees a criminal defendant the right "to be confronted with the witnesses against him." In June, the Supreme Court adapted that principle to the age of "CSI" by requiring prosecutors who use laboratory reports to call the experts who prepared them so that they can be cross-examined by the defense.
Now, after exaggerated complaints by some prosecutors, the court will revisit the issue in arguments on Monday. It should decline the invitation to rein in or reverse its ruling. Not for the first time, a court decision has forced prosecutors to change the way they do business and incur additional costs. And rightly so; the court shouldn't put a price tag on the exercise of a fundamental constitutional right.
Corrections has two points to make. The first is trivial, the second an unusual suggestion. Corrections notes that no matter what the court does, they will be putting a price on someone. Prosecutorial budgets are limited, as is the time of evidentiary experts. Putting no price on their time likely means to reduce their use by prosecutors. This, in turn, is likely to mean fewer convictions, and more crime.
Corrections notes that in a Coaseian manner, it is inconsequential to a trial's outcome if the state is not obligated to pay for evidentiary experts. If the expert's opinion is likely to absolve an individual, and that individual values not going to jail more than the cost of the expert's time, then they will hire that expert. Otherwise they will not. If the two parties are free to hire the service or not, then the outcome will be efficient, and just represent a wealth transfer.
If individuals are concerned that this wealth shift will be unfair or unjust, the state can, at worst, give all the wealth required to hire the evidentiary expert to a criminal. The criminal can either hire the expert, or keep the money. If they hire the expert, they do exactly what would have happened anyway. If they do not, then both parties are better off, as less court time and evidentiary expert time has been wasted.
The point is simple and worth reiterating. Enabling bilateral trade and exchange will make both parties better off. There is no exception to the right of a criminal to use the time of an evidentiary expert. There may be gains to trade from paying him not to waste everyone's time, a payment that by definition will make him better off (otherwise he would reject the offered trade!)