Virginia's 21-Day Rule
No new evidence is allowed to be introduced outside of a brief window of time, 21 days past sentencing. Called "finality of judgment." Means no new evidence of innocence can be used to exonerate an inmate unless it's discovered and brought forward within 21 days of the sentence being handed down. At first, this included DNA evidence, but later a second law was passsed to allow DNA evidence to be an exception to the rule. The law is based on the fact that trial courts are the only court where individuals in VA can introduce new evidence. The Virginia Supreme Court ruled that trial courts are no longer in charge of a case 21 days after sentencing.
Deciding Who Gets the DP in Texas and Florida
In Texas, the jury decides if the defendant is "a continuing threat to society" who would commit more violent crimes. In Florida, the jury may recommend that the defendant get the DP but it is up to the judge. Some FL judges have even changed a jury's decision of life in prison to a death sentence. Alabama also allows its judges to choose the death penalty after the jury has voted for life in prison.
Local Prosecutors decide if the DP will be sought in a case. They can also choose to offer a lighter sentence in exchange for a guilty plea.
If a state doesn't have a public defenders office, it assigns indigent cases to private practice lawyers but pays well below an average wage. For instance, Massachusetts pays a lawyer expenses plus $1,000 for a death penalty case. Many paralegals make more money than that. The result is that a low-income defendant facing a death sentence doesn't get a high-quality lawyer.

There are 2 amendments to the Constitution that are often referred to in the debate over the DP: the 8th and the 14th. The 8th Amendment is part of the Bill of Rights written in 1790 (2 years after the Constitution was ratified). It's known more commonly by the phrase "cruel and unusual punishment." Here is it's actual text:
"Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted."
The US Supreme Court has ruled that "cruel and unusual punishment" changes with the times along with what society accepts as appropriate behavior. For example, in the 1800s death by hanging was seen as OK. It later fell out of favor because of its association with outlaw lynchings and its slow and imperfect death rate. The Supreme Court refers to this as America's "evolving standards of decency."

The 14th Amendment was written 70 years later. It's known more commonly by the phrase "due process." Here is it's actual text:
"No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws."
This is generally interpreted to mean the right to a fair trial, with an impartial jury, a jury of your peers, and the right to take the stand in your own defense.