Some people will object that there needs to be a higher standard of evidence for the death penalty because execution is irreversible, but imprisonment is also irreversible. We can't rewind the clock and give back years of life wasted in prison. The best that we can do is compensate exonerated prisoners for the stolen time, which is often on the order of decades. This costs money, ideally quite a lot, and doesn't actually happen without incurring additional legal expenses, which also cost money. So one way or another, wrongful imprisonment is also a huge problem.
Am I missing something here? Are there actually any legitimate reasons for legal costs to be much higher when seeking the death penalty?
Part of this is just a realistic reflection of how resources get doled out. I'll use public defense to illustrate this case, because they deal with 80-90% of all criminal cases anyway. But when you start as a baby public defender, bullshit cases just get shoveled onto your trough even though you have no idea what the fuck you are doing. I distinctly recall my alarm when I was essentially shoved onto the main stage to 'represent' a client facing 30 days in jail at a probation hearing on my first day. Part of it was bad management from the PD office, but in retrospect most of it was just getting desensitized to the penalties. Once you have a few years of felony work where the sentencing denominator is casually spoken of in terms of months, misdemeanor jail sentences doled out in terms of days just seem so darn quaint in contrast.
Every state is going to be different, but they generally have a structured system of certifications and qualifications for the defense attorneys appointed to cases. Part of it is just brute self-interest: the system knows that if it doesn't adequately vet the public defenders, they'd get a steady stream of ineffective assistance of counsel claims overturning convictions on appeal. You can see this explicitly enshrined when you consider which attorneys are "death penalty certified". Just to pick one example from that list for California:
(2) Be an active trial practitioner with at least 10 years’ litigation experience in the field of criminal law;
(3) Have prior experience as lead counsel in either:
(A) At least 10 serious or violent felony jury trials, including at least 2 murder cases, tried to argument, verdict, or final judgment; or
(B) At least 5 serious or violent felony jury trials, including at least 3 murder cases, tried to argument, verdict, or final judgment;
All of that will necessarily winnow down the pool of candidates. "Death penalty certified" attorneys are a very rare breed because it's considered the apogee of the field, and you have to compensate accordingly. It's also not unusual to have multiple attorneys assigned to each case, compounded by the fact that capital cases are by definition complicated and take months to litigate (trials lasting months are normal).
When examining the economist cost of crime, analysts generally singularly focus on the cost of incarcerating individual prisoners. RAND tried to estimate the overall cost of prosecution by including costs from judges, courtroom staff, prosecutors, detectives, defense attorneys, experts, etc:
Researchers found that every reported homicide, for example, cost the judicial system $22,000 to $44,000. In other categories the costs were estimated at $2,000 to $5,000 for a rape or other sexual assault, $600 to $1,300 for a robbery, $800 to $2,100 for an aggravated assault, $200 to $600 for a burglary, $300 to $600 for larceny/theft, and $200 to $400 for a motor vehicle theft.
(I haven't taken a deep dive into this study, but some of these figures strike me as extremely low based on what I tend to get paid for my own cases, which represents only one sliver of the total cost. I'm guessing it's including 'reported but unprosecuted' cases?)
I agree with your point that "imprisonment is also irreversible". But I'm also mindful of the fact that it's just not realistic to appoint a ludicrously qualified professional for each petty crime.