a) The costs of a maximum death penalty sentence trial, resulting in a death penalty sentence, with pre trial, trial, appellate and incarceration costs, until execution or other death; and
b) Plea Bargains: Only a death penalty option can result in a LWOP plea bargain. Therefore, any LWOP plea bargain costs savings from pre trial, trial and/or appeals accrue as a cost credit on the death penalty side of the ledger;
2) LIFE WITHOUT PAROLE (LWOP) COSTS:
a) Death penalty eligible crimes, with a maximum LWOP sentence trial, resulting in a LWOP sentence, with pre trial, trial, appellate and incarceration costs, until death.
The reason you use death penalty eligible crimes as the standard, is because you are looking at equivalent cases, with two different sentencing protocols. Everything must be the same, except for the sentence, to get a true apples to apples cost comparison.
Of course, this will include geriatric care, which is considered to begin at ages 50-55, within the prison population.
b) Plea Bargains: Without the death penalty option, it will require more LWOP trials, because
1) Obviously, there will be no more pleas to LWOP and
This would have to be added, as an additional cost, to the LWOP side of the ledger, if one is considering ending the death penalty, as these additional costs will accrue, as a direct result of ending the death penalty.
You can get a reasonable estimate of those costs by counting;
1) all death penalty trials, resulting in either death or life;
2) all plea bargains to LWOP; and
3) all cases taken to a LWOP maximum trial.
All three of those categories of cases, by their prior handling, indicate that life WITH parole is not acceptable and, therefore, they MAY all require LWOP trials, if the death penalty were repealed.
NOTE: The cost benefit of the plea bargain, always goes to the greater sanction, as reviewed, just as it would if comparing costs of life without parole, the greater, to life with parole, the lesser.
3) Policy issues: Death Penalty - Saving Costs
A death row is not required. Neither Kansas nor Missouri have one.
b) Execution method:
Put corrections in charge of all execution methods, as they are, currently, in charge of implementing all other sanctions.
This will avoid time and money loss with changing the law through the legislature. It becomes a matter of procedural policy, not change in the law, just as most other procedural changes, within corrections. Give broad powers, such as "Any execution methods found constitutional or any other method of execution, that is, reasonably, considered to be constitutional."
Nitrogen Gas, for example.
c) Time for appeals:
In the modern death penalty era:
Nevada's first 11 executions occurred after about 4.5 years of appeals, on average.
Virginia's first 108 executions occurred after 7.1 years of appeals, on average.
Nationally, the first 60 executions occurred after about 6 years, on average.
Cases accepted at the US Supreme Court level are, relatively, rare. However, cases such as lethal injection method can effect all cases.