He is not 'capable of' making those medical decisions himself. [=he cannot make the decisions by himself because he cannot think clearly, he is too sick, etc.]
I don't believe that she's 'capable of' murder. [=that she is the kind of person who could murder someone]
She is one of the most 'capable' [='skilled'] and versatile actresses in Hollywood.
(..) Elsa? It's me... Anna. Anna? Wow... Elsa, you look different... It's a good different...And this place. Is amazing...Thank you. I never knew what I was capable of. I'm so sorry about what happened. If I'd known... No, it's okay. You don't have to apologize. But you should probably go, please. (..)2013 Frozen
(..) Just say it, you little devil. Say it: you tricked the magician. Occasionally, a touch of deception goes a long way. Bones, even you are capable of a little magic. Which is why I slipped a dollar under Christine's pillow when I kissed her good night. See? A little mystery (..)2015 TvShow: Bones Title: The Promise in the Palace Season: 11 Episode 7
(..) in the wrong Dumpster at the wrong time. No, not this time. This time my gut is saying murder. No. The only time a gut should be capable of opening a murder investigation is when that gut contains poison. Or a stab wound. Or a stab wound, yes. A stab wound to the gut (..)2016 TvShow: Bones Title: The Movie in the Making Season: 11 Episode 18