The death penalty should be reserved for only the most culpable of criminals. A small percentage of the people eligible for the death penalty ever receive that sentence, and of them, very few are actually executed. People with mental retardation are, by definition, the bottom two and a half percent of the population as measured by intelligence tests. So how can there be overlap between those groups -- the top 2 percent of murderers with the highest degree of understanding, the most responsible for those crimes, and the 2 percent of people who have mental retardation? Who could fit in both those categories? It is an empty set.

And there's the question of whether a person with mental retardation would have committed the crime were it not for his disability. People with mental retardation are more susceptable to suggestion and more eager to please. Therefore, outside influences could lead them to commit crimes that they would not otherwise be involved with. Mental retardation also makes it more difficult to contribute to your own defense, so they face disadvantages throughout court proceedings.

This is not to say that people with mental retardation should not be punished for crimes. In noncapital cases, it may be appropriate to sentence a person with mental retardation the same way a nondisabled person would be sentenced.

Is that a type of reverse discrimination, where people with mental retardation are not held to the same standards of obeying the law?

We treat people with mental retardation differently than we treat people without that disability in lots of other contexts, and those distinctions are reasonable. My position is that it's equally reasonable to say that when we execute people, we are looking for those with the highest degree of culpability and understanding. If that system is putting people with mental retardation on death row, then the system isn't working the way its supporters want the system to work.

One of the standards held by the public for capital cases is that the condemned has to understand the enormity of the crime -- and the difference between right and wrong. Given that Cruz has been so forthcoming about his level of responsibility, is it reasonable for the public to conclude that his execution is justified?

The question of whether someone has a sufficient understanding of right and wrong doesn't tell us how you punish somebody. Instead, it tells us whether you can convict them at all. So one way to think about this is that we are talking about different levels of understanding. Somebody who understands the wrongfulness of their actions is someone who can be convicted and punished. The death penalty takes that same commodity -- a person's understanding of his acts -- and says that only those at the highest level of understanding should be subject to execution.

Texas has a dubious record for executing people on thin evidence. But given that Cruz confessed to his crime, how likely do you think it is that Texas will grant a stay?

Cases in other states involving defendants with mental retardation should give Texas pause. The one that's probably most familiar to your readers, although they may not have thought of it as a mental retardation case, is that of Anthony Porter, who a year and a half ago walked off Illinois' death row because journalism students had discovered that he was the wrong guy. Everyone has focused on that as a factual innocence case, but the reason Porter was alive to be proven innocent by those students is because 72 hours before his execution he received a stay from the Illinois Supreme Court, which said, "Let's figure out if we want to execute someone with mental retardation in the state of Illinois."

I had the privilege of representing Porter in the matter of his mental retardation. I didn't know he was innocent at that time, but because we won that stay, Porter was alive long enough for those students to prove his innocence.

Have you resigned yourself to Cruz's execution?

Stays come even when you don't expect them, and often at the last moment. But I think whenever an execution gets close in Texas, you have to be realistic.

Politics 2000: Unflinching daily political news, analysis and commentary.