This may seem obvious, but if it's not, this opinion makes the underlying principle clear:
Just because someone's going to eventually die doesn't mean you can kill him. It's still murder.
Juan Cordova was an elderly, homeless guy with serious liver and heart conditions. The coroner says he'd likely have died within three or four years.
Mark Mijares had a serious drug problem. After taking methamphetamine and staying awake for a full week, in a drug-induced psychosis, he inexplicably focused on Mr. Cordova, shouting "I'm going to take you out." He then pummeled Mr. Cordova with a brick, punched him, kicked him, covered his head with a plastic bag, and stabbed him in the neck, killing him. Mr. Cordova didn't die instantly, but instead lingered in the hospital for a week before dying of his injuries.
Mr. Mijares argues on appeal that his offense might only be attempted murder because Mr. Cordova would have died anyway. Quite understandably, the Court of Appeal disagrees.
Yep.