"To those who point out the miscarriages of justice on innocent people I agree that’s awful and that the death penalty needs to be only used in cases which are beyond doubt" that's never going to be possible.
All the cases people cited of miscarriages of justice, at the time of conviction the juries, judges and usually the general public/society and in some of those cases even their loved ones thought - believed - they were guilty beyond a reasonable doubt.
"If every rapist, and sadistic murderer were given life sentences then we would run out of prison space." Not true if we STOPPED imprisoning financial criminals, low level criminals - theft, handling stolen goods, shoplifting, drug possession etc
There are as some pps have commented on a lot of low level criminals in prison who are mentally ill, have learning disabilities, drug or alcohol addiction, or who have missed out on a decent education for other reasons.
And those have been major factors in their committing those crimes. Drug and alcohol treatment, dx & treatment of mental illness, dx & treatment/support for learning disabilities, education for those who missed out... Would be far more effective in rehabilitating these people as criminals and in preventing them from committing further crime.
Leaving prison spaces for the most dangerous, violent criminals.