Despite the jury returning a verdict of 11 to 1 that his life should be spared, but the judge applied a since-repealed Alabama statute to override the jury, which was found to be unconstitutional by the United States Supreme Court.

Seriously, the US system is a mess that this was allowed to happen. Along with the US only a few counties still have the death penalty, and many of them haven't done one for >20 years, meaning it is effectively gone.

Some animals are sensitive to oxygen deprivation. Humans are not.

Ask why you weren't told this.