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