There are a lot of procedural protections for defendants already. A jury of their peers has to vote unanimiously that aggregating factors outweigh mitigating factors beyond a reasonable doubt, with every aggravating factor needing proof beyond a reasonable doubt and each motivating factor requiring only a modest amount of evidence to prove.

The only serious argument against this is that the trial process for rape is too open to abuse, which is the same for murder… either way if that’s the case rape should at least be punishable with LWOP to allow exoneration if that happens.