Our criminal justice system is fallible. We know it, even though we don't like to admit it. It is fallible despite the best efforts of most within it to do justice. And this fallibility is, at the end of the day, the most compelling, persuasive, and winning argument against a death penalty.
If you know anything about the issues in our country, you know we have a lot of deep-rooted anger and anxieties that spark a lot of passion. When you talk about our national anthem or the flag or race relations or the criminal justice system, it brings up a lot of those fears and insecurities.
It is no longer socially permissible to use race, explicitly, as a justification for discrimination, exclusion, and social contempt. So we don't. Rather than rely on race, we use our criminal justice system to label people of color 'criminals' and then engage in all the practices we supposedly left behind.